I was wondering if ASP.NET MVCF be used with a Postgresql database?
If you want to use both .NET and Postgresql then use Npgsql:
Npgsql is a .Net Data Provider for Postgresql. It allows any program developed for .Net framework to access database server. It is implemented in 100% C# code. Works with Postgresql 7.x and above.
ASP.NET MVC is a web framework for creating web applications - it doesn't care what you use for a persistence store behind the scenes. You are free to implement any store you wish (database, flat file, etc.).
One of the benefits of orthogonal architectures is that they give you the freedom to change everything from small components to entire archetectural tiers with minimal impact to the rest of the system. ASP.NET MVC was built with this philosophy.
You could also use dotconnect for PostgresSQL. As Andrew says ASP.Net MVC does not place any requirements on your database layer.
http://www.devart.com/dotconnect/postgresql/articles/tutorial_ef.html