I did a quick search and haven't seen it mentioned here.
Just a heads up, if you have two R2 DHCP servers in a split scope configuration, you'll need to install this hotfix;
KB981776 - Reservations are deleted incorrectly from a DHCP server that is running Windows Server 2008 R2
(Can't post a link as I'm too new)
Now I have it installed, I better go and recreate all my deleted reservations.....