Two weeks ago, Microsoft published a Release Candidate (RC) of Entity Framework 4.1. They promised to release the product within 4 weeks.
Well, they released it today!
So you can now use Entity Framework 4.1 which is a fully supported Microsoft Product.
The only change done from the RC is the default length of nvarchar from 128 to MAX.
You can follow my series of blog on Entity Framework 4.1 to learn more about the technology.