Heads-UP, friends. Even if you have already installed the patches for every Windows Server and every Exchange 2007, there still is more to do. Microsoft has issued Rollup 6 for Exchange 2010 SP1 which contains one more update to your CAS servers which affects DST cancellation. If you still see +3 time zone for Russia and other countries then you need to install it.
Here is the Rollup: http://support.microsoft.com/kb/2608646
And here is the KB about problem with CAS Servers: http://support.microsoft.com/kb/2627769
I Hope you’ll get fine through all this stuff =)