ORMBattle.NET

Summary from product page:

"NHibernate is a mature, open source object-relational mapper for the .NET framework. It's actively developed, fully featured and used in thousands of successful projects."

Tested version: 2.1.2 GA

Test code:

• LINQ implementation (comment against each test describes if it passes or fails)
• Performance

License:

• Freeware (LGPL)
• Open source

Links:

• Product page
• Wikipedia page
• Blog
• Community site
• Downloads
• Wikis