There have been a lot of rumors going around that Miccrosoft will not be supporting Exchange 2007 on the new WIndows 2008 R2 release.  I can reassure you that this is not true.  After speaking with several folks at Microsoft I have gotten an answer for everyone and you can all relax. 

Here is what I found out.   There are some compatibility issues with running Exchange 2007 on Windows 2008 R2.  Engineering is still working through those issues.  They are very positive that this will work as they continue to resolve some of the compatibility issues. 

We will have to wait and see as the issues are worked out, but it is looking like the supported configuration will end up having to be Exchange 2007 Service Pack 2 runnning on Windows 2008 R2.