diff --git a/pkgs/development/libraries/postgis/default.nix b/pkgs/development/libraries/postgis/default.nix
index 41068c4e39a1..016bd23cf1ca 100644
--- a/pkgs/development/libraries/postgis/default.nix
+++ b/pkgs/development/libraries/postgis/default.nix
@@ -1,51 +1,151 @@
-{stdenv, fetchurl, libxml2, postgresql, geos, proj, perl}:
+args@{fetchurl, composableDerivation, stdenv, perl, libxml2, postgresql, geos, proj, flex, ...}:
 
-# TODO: the bin commands to have gtk gui
-# compile this optionally ?
+  /*
 
-# NixOS - usage: services.posgresql.extraPlugins = [ pkgs.postgis ];
+  ### NixOS - usage:
+  ==================
 
-stdenv.mkDerivation {
-  name = "postgis";
+    services.posgresql.extraPlugins = [ pkgs.postgis.v_1_5_1 ];
 
-  src = fetchurl {
-    url = http://postgis.refractions.net/download/postgis-1.5.1.tar.gz;
-    sha256 = "0nymvqqi6pp4nh4dcshzqm76x4sraf119jp7l27c2q1lygm6p6jr";
-  };
+    or if you want to install 1.5.x and 1.3.x at the same time (which works
+    because the .sql and .so files have different names):
 
-  makeFlags = "PERL=${perl}/bin/perl";
+    services.postgis.extraPlugins = [ (pkgs.buildEnv {
+          name = "postgis-plugins";
+          ignoreCollisions = 1; # scripts will collide - but there are aliases with version suffixes
+          paths = [ pkgs.postgis.v_1_3_5 pkgs.postgis.v_1_5_1 ];
+        })];
 
-  # default both defaul to postgis location !?
-  preConfigure = ''
-    configureFlags="--datadir=$out/share --datarootdir=$out/share --bindir=$out/bin"
-    makeFlags="PERL=${perl}/bin/perl datadir=$out/share pkglibdir=$out/lib bindir=$out/bin"
+    By now it is only supported installing one of the 1.3.x verions because
+    their shared libraries don't differ in naming.
 
-  #  makeFlags="DESTDIR=$out "
-  '';
 
-  # create a script enabling postgis features
-  postInstall = ''
-    cat >> $out/bin/enable_postgis_for_db << EOF
-    #!/bin/sh
-    set -x
-    t=$out/share/contrib/postgis-1.5
-    for db in "\$@"; do
-      createlang plpgsql \$db
-      for f in postgis spatial_ref_sys; do
-        psql -d \$db -f \$t/\$f.sql
+
+  ### important Postgis implementation details:
+  =============================================
+
+    Postgis provides a shared library implementing many operations. They are
+    exposed to the Postgres SQL interpreter by special SQL queries eg:
+
+      CREATE FUNCTION [...]
+              AS '[..]liblwgeom', 'lwhistogram2d_in' LANGUAGE 'C' IMMUTABLE STRICT; -- WITH (isstrict);
+    
+   where liblwgeom is the shared library.
+   Postgis < 1.5 used absolute paths, in NixOS $libdir is always used.
+
+   Thus if you want to use postgresql dumps which were created by non NixOS
+   systems you have to adopt the library path.
+
+
+
+   ### TODO:
+   =========
+   the bin commands to have gtk gui:
+  */
+
+
+let
+  pgDerivationBase = composableDerivation.composableDerivation {} ( fix :
+
+  let version = fix.fixed.version; in {
+
+    name = "postgis-${version}";
+
+    src = fetchurl {
+      url = "http://postgis.refractions.net/download/postgis-${fix.fixed.version}.tar.gz";
+      inherit (fix.fixed) sha256;
+    };
+
+    # don't pass these vars to the builder
+    removeAttrs = ["hash" "sql_comments" "sql_srcs"];
+
+    preConfigure = ''
+      configureFlags="--datadir=$out/share --datarootdir=$out/share --bindir=$out/bin"
+      makeFlags="PERL=${perl}/bin/perl datadir=$out/share pkglibdir=$out/lib bindir=$out/bin"
+    '';
+
+    pg_db_postgis_enable = ./pg_db_postgis_enable.sh;
+
+    scriptNames = [ "pg_db_postgis_enable" ]; # helper scripts
+
+    # prepare fixed parameters for script and create pg_db_postgis_enable script.
+    # The script just loads postgis features into a list of given databases
+    postgisEnableScript = ''
+      s=$out/bin/pg_db_postgis_enable
+
+      sql_comments=$out/share/postgis-${version}/comments.sql
+      ensureDir $(dirname $sql_comments)
+      cp $(find -iname ${fix.fixed.sql_comments}) $sql_comments
+
+      for script in $scriptNames; do
+        tg=$out/bin/$script
+        substituteAll ''${!script} $tg
+        chmod +x $tg
       done
-    done
-    EOF
-    chmod +x $out/bin/enable_postgis_for_db
-  '';
+    '';
 
-  buildInputs = [libxml2 postgresql geos proj perl];
+    # create a script enabling postgis features
+    # also create aliases for all commands adding version information
+    postInstall = ''
+
+      sql_srcs=$(for sql in ${builtins.toString fix.fixed.sql_srcs}; do echo -n "$(find $out -iname "$sql") "; done )
+
+      eval "$postgisEnableScript"
+      eval "$postgisFixLibScript"
+
+      for prog in $out/bin/*; do
+        ln -s $prog $prog-${version}
+      done
+
+      cp -r doc $out
+    '';
+
+    buildInputs = [libxml2 postgresql geos proj perl];
+
+    sql_comments = "postgis_comments.sql";
+
+    meta = {
+      description = "Geographic Objects for PostgreSQL";
+      homepage = "http://postgis.refractions.net";
+      license = "GPLv2";
+      maintainers = [stdenv.lib.maintainers.marcweber];
+      platforms = stdenv.lib.platforms.linux;
+    };
+  });
+
+
+in rec {
+
+  # these builders just add some custom informaton to the receipe above
+
+  v_1_3_5 = pgDerivationBase.merge ( fix: {
+    version = "1.3.5";
+    buildInputs = [ flex ];
+    sha256 = "102d5ybn0db1wrb249dga2v8347vysd4f1brc8zb82d7vdd34wyq";
+    sql_srcs = ["lwpostgis.sql" "spatial_ref_sys.sql"];
+
+    pg_db_postgis_fix_or_load_sql_dump = ./pg_db_postgis_fix_or_load_sql_dump.sh;
+    libName = "liblwgeom";
+    scriptNames = [ "pg_db_postgis_enable" "pg_db_postgis_fix_or_load_sql_dump"]; # helper scripts
+
+    # sql_srcs is defined in postInstall source above
+    # if store path changes sql should not break. So replace absolute path to
+    # shared library by path relatve to $libdir known by Postgres.
+    postInstall = ''
+      sed -i "s@AS '$out/lib/liblwgeom@AS '\$libdir/liblwgeom@" $sql_srcs $out/share/lwpostgis_upgrade.sql
+    '';
+  });
+
+  v_1_3_6 = v_1_3_5.merge ({
+    version = "1.3.6";
+    sha256 = "0i6inyiwc5zgf5a4ssg0y774f8vn45zn5c38ccgnln9r6i54vc6k";
+  });
+
+  v_1_5_1 = pgDerivationBase.merge ( fix : {
+    version = "1.5.1";
+    sha256 = "0nymvqqi6pp4nh4dcshzqm76x4sraf119jp7l27c2q1lygm6p6jr";
+    sql_srcs = ["postgis.sql" "spatial_ref_sys.sql"];
+  });
 
-  meta = {
-    description = "Geographic Objects for PostgreSQL";
-    homepage = "http://postgis.refractions.net";
-    license = "GPLv2";
-    maintainers = [stdenv.lib.maintainers.marcweber];
-    platforms = stdenv.lib.platforms.linux;
-  };
 }
+
diff --git a/pkgs/development/libraries/postgis/pg_db_postgis_enable.sh b/pkgs/development/libraries/postgis/pg_db_postgis_enable.sh
new file mode 100644
index 000000000000..c7652e20d9f3
--- /dev/null
+++ b/pkgs/development/libraries/postgis/pg_db_postgis_enable.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+sql_files=(@sql_srcs@)
+sql_comments=@sql_comments@
+
+do_help(){ echo "$0 [--comments] db_name1 [db_name2 ..]"; }
+
+for arg in "$@"; do
+  case "$arg" in
+    -h|--help)
+      do_help; exit 0
+      ;;
+    --comments)
+      LOAD_COMMENTS=1
+    ;;
+    *)
+      dbs=(${dbs[@]} "$arg")
+    ;;
+  esac
+done
+
+PSQL(){
+  echo ">> loading $1"
+  psql -d "$db" -f $1
+}
+
+for db in ${dbs[@]}; do
+  createlang plpgsql "$db"
+
+  # mandatory
+  for sql in $sql_files; do
+    PSQL $sql
+  done
+
+  # optionally load some comments
+  if [ -n "$LOAD_COMMENTS" ]; then
+    PSQL $sql_comments
+  fi
+done
diff --git a/pkgs/development/libraries/postgis/pg_db_postgis_fix_or_load_sql_dump.sh b/pkgs/development/libraries/postgis/pg_db_postgis_fix_or_load_sql_dump.sh
new file mode 100644
index 000000000000..6a98c5d24ca8
--- /dev/null
+++ b/pkgs/development/libraries/postgis/pg_db_postgis_fix_or_load_sql_dump.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+libName=@libName@
+
+# this is a quick and dirty implementation
+
+do_help(){
+  echo "$0 --str str in-file|- [out|-|psql:db]";
+  echo "in: - = STDIN or filename";
+  echo "out: - = STDIN or filename or psql:database_name" 
+  echo "         psql:database_name will load the dump into the database" 
+  echo "         if out is omitted in is used for out (same file)"
+  echo "--str: different replacement string. Eg for Ubuntu use: '/usr/lib/postgresql/8.3/lib/liblwgeom'";
+  echo "WARNING: A postgis dump is not meant to be distributed - it still may be useful :)"
+}
+
+if [ -z "$1" -o "$1" = --help -o "$1" = -h ]; then
+  do_help; exit 1
+fi
+
+tostr='$libdir/'"$libName"
+if [ "$1" == "--str" ]; then
+  to="$2"; shift 2
+fi
+
+i=$1
+o="${2:-$1}"
+
+cmd_in(){
+  case "$i" in
+    -) cat;;
+    *) cat "$i";;
+  esac
+}
+
+cmd_out(){
+  case "$o" in
+    -) cat;;  # stdout
+    psql:*) psql "${o:5}";; # pipe into psql
+    *)
+      t=`mktemp`; cat > "$t"; mv "$t" "$o"
+      ;;
+  esac
+}
+
+cmd_replace(){
+  contents=`cat`
+  # get wrong library path:
+  fromstr=$(echo "$contents" | head -n 50 | sed -n "s/.*AS '\([^']*\)'.*/\1/p" | head -n 1)
+  echo "$contents" | sed "s@AS '$fromstr@AS '$tostr@g"
+}
+
+cmd_in | cmd_replace | cmd_out
diff --git a/pkgs/lib/misc.nix b/pkgs/lib/misc.nix
index 0a8c61d6c85c..32b30ee2fbff 100644
--- a/pkgs/lib/misc.nix
+++ b/pkgs/lib/misc.nix
@@ -294,7 +294,7 @@ rec {
   mergeAttrBy = # { buildInputs = concatList; [...]; passthru = mergeAttr; [..]; }
     listToAttrs (map (n : nameValuePair n lib.concat) [ "buildNativeInputs" "buildInputs" "propagatedBuildInputs" "configureFlags" "prePhases" "postAll" ])
     // listToAttrs (map (n : nameValuePair n lib.mergeAttrs) [ "passthru" "meta" "cfg" "flags" ])
-    // listToAttrs (map (n : nameValuePair n (a: b: "${a}\n${b}") ) [ "preConfigure" ])
+    // listToAttrs (map (n : nameValuePair n (a: b: "${a}\n${b}") ) [ "preConfigure" "postInstall" ])
   ;
 
   # returns atribute values as a list 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 76f3f0212282..0ac2592b0a82 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5067,7 +5067,8 @@ let
   };
 
   postgis = import ../development/libraries/postgis {
-    inherit stdenv fetchurl libxml2 postgresql geos proj perl;
+    inherit stdenv fetchurl libxml2 postgresql geos proj perl flex
+      composableDerivation;
   };
 
   pth = import ../development/libraries/pth {