Object Data Blocks is object persistence style ORM for new database implementations. Define you data layer using classes to define tables and fields and decorate them with attributes to define keys, indexes, constraints etc. A provider model for a specific relational database (currently sql server 2005 or later) takes care of the rest. Any changes to the assembly can be deployed at runtime seamlessly to the database without any loss of data.
Read more information and view code samples here.
Object Data Blocks is released under the GPL 2.0 licence and is hosted at http://objectdatablocks.codeplex.com