Two important LINQ implementations: LINQ to XSD and LINQ to SharePoint
There are two very important LINQ implementations to keep your eye on as we near the release of Visual Studio 2008, LINQ to XSD and LINQ to SharePoint.
LINQ to XSD is a Microsoft effort that allows you to perform LINQ queries against strongly typed XML documents. This is a much better experience than you will get with LINQ to XML. See the links provided by Roger Jennings in his post on LINQ to XSD for examples of the difference. Using LINQ to XSD will give a much better developer experience that vanilla LINQ to XML. LINQ to XSD was released as Alpha in the Orcas Beta 1 release.
LINQ to SharePoint is a Codeplex effort now in Alpha. Because it converts LINQ queries to SharePoint CAML queries, this is a great application of LINQ. I would definitely keep my eye on this implementation, since SharePoint is growing in importance and capability in the industry. More details in this Roger Jennings post.