I really like the new Entity Framework Code First. The best feature I like is the offloading the overhead creation of Data Model or Database itself which EF takes care on its own. It also supports setting up initial seed data in the table too. Wow!!! This is the feature I have been longing for a while.
Walkthru video can be found here.
In conjunction with Asp.net MVC3 EF Code First in EF 4.1 is the robust platform to develop Web applications.