Check out the blogs below. You can find plenty of tech tips & tricks right from the guys, who are working on the MSSQL server team.
http://blogs.msdn.com/sqlqueryprocessing/
http://blogs.msdn.com/sqlprogrammability/
http://blogs.msdn.com/sqlserverstorageengine/
http://blogs.msdn.com/sqlcat/
http://blogs.msdn.com/sqlclr/
