Microsoft have just released the Microsoft CRM 4.0.12 SDK, which has a number of new developer features.
I'm still going through them, but I'm liking what I see.
One that stood out to me is that they now have a CRM 4.0 LINQ provider included! Yay!
To download the SDK and check it out, find it here:
http://www.microsoft.com/downloads/details.aspx?FamilyID=82E632A7-FAF9-41E0-8EC1-A2662AAE9DFB&displaylang=en
Cheers
Matt