I just read this blog post on ADO.NET team blog.  I have been wondering about the future on Linq to SQL since the release of Entity Framework.  There is signification overlap in capabilities of both technologies, and one must wonder about the overhead Microsoft is willing to incur in maintaining both.  My guess is, they will not do this forever.  So, if you are starting a new application, would you use Linq to SQL today.  My answer is no.