Did you know that along with the early CTPs of Orcas, there are VB and C# solutions that each contain hundreds and hundreds of LINQ Query samples? They diplay the code, the translation into TSQL and when executed, the results.
This is definitely very old news to some, however I originally was merely looking at the source code and only recently thought to actually run the sample, and boy was I astonished at the results! In each solution there are101 query examples for 4 flavors of LINQ Queries. LINQ to Objects, LINQ to SQL (was called DLinq at the time), XLINQ and LINQ to Dataset. Linq to Entities was not quite ready yet so it's not in there.
Although LINQ syntax and some functionality are still evolving, the queries are, for the most part, totally valid and very educational.
There are two new posts on the ADO.NET blog about LINQ to DataSets, showing where that one will be when it's finished. I'm really looking forward to the next CTP, but in the meantime, there's a lot to learn here!
Some Resources: