The information in this post is out of date.
Visit msdn.com/data/ef for the latest information on current and past releases of EF.
The ADO.NET Entity Data Model Designer Extension Starter Kit has been updated to work with Visual Studio 2010 RC bits.
Get the latest version here: http://code.msdn.microsoft.com/DesignerExtStartKit.
– Julia Kornich,
Content Publisher, Entity Framework