EDIT: 2008-08-12 - ES2008 uses our own esLanguages.xml with the PostgreSQL mappings EntitySpaces expects. The following instructions are no longer necessary, and only apply to ES2007. 

MyGeneration ships with the PostgreSQL native column type to C# mappings named differently than the EntitySpaces templates expect them. However, this can be easily corrected in a few quick seconds by following these these steps (VB.NET users follow these same steps, EntitySpaces uses only the C# mappings even for VB.NET):

• Open MyGeneration
• Connect to your PostgreSQL database using the MyGeneration Default Settings dialog. It's under the "Edit -> Default Settings ..." menu
• Click on the "Language Mappings" toolbar button (4th from the right - use tooltips)
• Select "C# (Npgsql)" in the drop down combobox in the "Language Mappings" dockable window.
• Click on the "Create New Language Mapping" icon (white icon on the "Language Mappings" dockable window)
• In the popup dialog for the Language type in C# and Based Upon select C# (Npgsql)
• Click on the "OK" button
• Click on the "Save" icon on the  "Language Mappings" dockable window
• Close and reopen MyGeneration, you're all set.

The above instructions are a one time operation, you will not have to do them again.

EDIT: 2007-12-15 - Corrected from "C# System Types" to "C# (Npgsql)"