Dinesh Kulkarni, a Program Manager on the LINQ team, has written a blog post listing what's new in LINQ to SQL with the newly released Beta2.

I already went looking to make sure the promised LINQDataSource was there (since I included it in the abstract for my November DevConnections talk), but his list is also showing me things I haven't discovered on my own yet, such as the fact that the command line SQL Metal tool and the visual designer will produce the same results, additional support for finding changed objects, better visual tools for handling stored procs and my favorite on his list: "500+ fewer bugs".

You can read the full list here in his blog post.