Geomar, I am currently going through the ASP.NET MVC 2 book (with NerdDinner) trying to use EFv1. The first EF version was not ready for prime time; tasks that were simple in LINQ to SQL are major issues in EFv1. Such as mapping a database scalar-valued function.
Version 1 of Entity Framework (EFv1) was included with .NET Framework 3.5 Service Pack 1 and Visual Studio 2008 Service Pack 1, released on 11 August 2008. This version has been widely criticized, even attracting a 'vote of no confidence' signed by several hundred developers.
The second version of Entity Framework, named Entity Framework 4.0 (EFv4), was released as part of .NET 4.0 on 12 April 2010 and has addressed many of the criticisms made of version 1.
A third version of Entity Framework, yet unnamed, is planned for release in first quarter of 2011. There have been several betas (called Community Technology Preview) of it and the last CTP5 was released in December 2010.