Updated postgres to add the map, and modified the init to support this. Updated readme as well.

postgres/init.sls

@@ -1,9 +1,7 @@
-# pkg.install
-postgresql:
-  pkg.installed:
-    {% if grains['os_family'] == 'RedHat' %}
-    - name: postgresql
-    {% elif grains['os_family'] == 'Debian' %}
-    - name: postgresql-9.1
-    {% endif %}
+{% from postgres/map.jinja import postgres with context %}
+
+postgresql:
+  pkg:
+    - installed
+    - name: {{ postgres.pkg }}
 

postgres/map.jinja

@@ -0,0 +1,8 @@
+{% set postgres = salt['grains.filter_by']({
+    'Debian': {
+        'pkg': 'postgresql-9.1',
+    },
+    'RedHat': {
+        'pkg': 'postgresql',
+    },
+}, merge=salt['pillar.get']('postgres:lookup')) %}