Microsoft has officially announced that OCS 2007 R2 will be supported starting in Q1 2010. They don’t give an exact date in Q1, but check it out on this page dedicated to listing apps officially supported by Microsoft on Windows 2008 R2.
Mark Russinovich of Sysinternals fame, has announced that he is retiring the NewSID utility. After questioning the common belief that duplicate SIDs posed a risk, he offers a compelling rationale why this is false and that we have been duped. The debate that follows in the comments leads me to the conclusion that machine images used for deployment should always be SysPrepped!