Over at Simple-Talk.com, Steven R. McCabe has a great article about working with LINQ and using it to create a DAL/Entity layer for your application. There is no mention of Silverlight or WPF, but the article talks about things such as CRUD (Create, Read, Update, Delete) operations with LINQ and explains the subject very well with code examples. While some of it is from CTP previews (which you no longer need because it's been released), the explanation of the subject is well worth the read.

 There have been quite a few people blogging and doing LINQtoSQL with Silverlight Tutorials lately but nothing that shows how to do operations in LINQ that you'd need for a real application. This article fills in those gaps nicely..