It started with ASP.NET (MVC, WebForms, WebApi, etc...) and now they've gone and opened up the source for Entity Framework!

Microsoft have just announced that Entity Framework is open source, where developers can fork the source repository and make their own ad-hoc changes, submit bug fixes or implement it in their very own special way.

Another gold star to Microsoft for getting more involved in the open source arena.

Checkout ScottGu's and Hanselman's posts about it for more information.