Those of you who have tried have probably already encountered this, but it’s good to state it anyway: Due to the changes made in ConfigMgr SP2 beta to support Windows 7 deployment, MDT 2008 Update 1 (or any previous version) will not work with ConfigMgr SP2 beta. This is primarily due to the use of the new Windows Automated Installation Kit for Windows 7 RC (a.k.a. Windows AIK 2.0).
Once MDT 2010 Beta 2 is released (very soon – yes, I know I’ve been saying that for a while, but it really is), you will be able to use it with ConfigMgr SP2 beta.
There are no plans to release additional updates for MDT 2008 or BDD 2007 – all our efforts are now focused on MDT 2010.