Today we posted a beta update to solve a couple of problems with Dynamic Data and Entity Framework that are in the RTM version of .NET 3.5 SP1. The main issue is a slight mis-match in the names that Dynamic Data looks for in Entity Framework and the names that Entity Framework is actually exposing. When this problem occurs an error that looks like "A property with name ‘XX.Id’ does not exist in metadata for entity type ‘XX.XX.XXXX’".
Luckily we made the data model providers which are classes that look at data model and tell Dynamic Data what the tables, columns, names, etc are a extensible system. This means we can distribute a replacement data model provider that solves the issue I mentioned above. You can download a replacement Entity Framework provider at this link: http://www.codeplex.com/aspnet/Release/ProjectReleases.aspx?ReleaseId=16367
If you are running into this issue please download the fix above and let us know if it solves your issues.