Today Microsoft released Update Rollup 2 for Exchange 2010 Service Pack 2. One of the thing I really want to mention is that the problems with CAS-CAS proxy now is solved. KB2696913 (not currently available but that will be fixed soon) describes the problem.
Download link for Exchange 2010 SP2 Update Rollup 2.
Link to the complete list of issues that RU2 solves, KB2661854
Check out the blog over at the Exchange Team Blog for their comment and don’t forget to disable Forefront (if installed on your server) before you install the update.