You may have noticed that a new AIK was released, more information about this can be found at Niehaus blog:
http://blogs.technet.com/b/mniehaus/archive/2011/02/17/windows-aik-for-windows-7-sp1-released.aspx
Note that CM team is testing W7 SP1 and WinPE 3.1 and until testing is completed it is unsupported