One thing I just noticed in their favor was in Raman's post, he mentioned the use of One Time Initialization APIs (e.g. InitOnceExecuteOnce).  I don't find this or any related APIs in the consumer preview beta (I did a find in files).  However if Raman is correct, I'm guessing that this has been added post-beta.  So we'll have to wait for RC or RTM to know the true extent of the dependency on Vista.  That worries me, as it could blow the workaround I presented right out of the water.