If you have recently deployed FIM 2010 on Windows 2008 R2 and tried to install the Exchange 2007 SP2 or earlier Management tools (required for exchange 2007 mailbox provisioning via the AD MA), you would have noticed that the SP2 or below was not supported on Windows 2008 R2. Fortunately Exchange 2007 SP3 solves this problem by adding support for Windows 2008 R2.
You can download Exchange 2007 SP3 at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=1687160b-634a-43cb-a65a-f355cff0afa6&displaylang=en
