UPDATED: January 2013
Recently I have encountered several issues with Exchange 2010 servers, only to find out that there is a hotfix for the problem. So in an effort to get ahead of these issues, I decided to collect my own short list of hotfixes for that I have recommended for an Exchange 2010/Windows 2008 R2 environment. NOTE: This does not include security hotfixes (WSUS) and is NOT an official list of hotfixes or build recommendation - this is my list of hotfixes that I have recommended for newly deployed Exchange environments as a means to prevent known issues from occurring.
Exchange 2010 Hotfixes Exchange 2010 Service Pack 2 - http://www.microsoft.com/download/en/details.aspx?id=28190 KB2785908 Update Rollup 5-v2 for Exchange Server 2010 Service Pack 2 - http://support.microsoft.com/kb/2785908
Office 2010 Hotfixes Office 2010 Service Pack 1 - http://support.microsoft.com/kb/2460049 KB2687623 Description of the Outlook 2010 update: November 13, 2012 - http://support.microsoft.com/kb/2687623 KB2553391 Description of the Outlook 2010 hotfix package: December 11, 2012 - http://support.microsoft.com/kb/2553391 KB2789671 Office 2010 cumulative update for December 2012 - http://support.microsoft.com/kb/2789671
Office for Mac 2011 Hotfixes KB2764047 Description of the Microsoft Office for Mac 2011 14.2.5 Update - http://support.microsoft.com/kb/2764047 Windows 2008 R2 Post-SP1 Hotfixes KB2754704 http://support.microsoft.com/kb/2754704 -- MPIO KB2756999 http://support.microsoft.com/kb/2756999 -- RPCSS KB2743555 http://support.microsoft.com/kb/2743555 -- KERBEROS KB2536276 http://support.microsoft.com/kb/2536276 -- MRXSMB KB2727972 http://support.microsoft.com/kb/2727972 -- VOLSNAP KB2769701 http://support.microsoft.com/kb/2769701 -- STORPORT KB2471472* http://support.microsoft.com/kb/2471472 -- NDIS KB2769369 http://support.microsoft.com/kb/2769369 -- WIN32SPL KB2494016* http://support.microsoft.com/kb/2494016 -- CSVFILTER KB2750841 http://support.microsoft.com/kb/2750841 – NCSI/TCPIP KB2578113* http://support.microsoft.com/kb/2578113 -- CLUSRES KB2614892* http://support.microsoft.com/kb/2614892 -- MOUNTMGR KB2617858* http://support.microsoft.com/kb/2617858 – WMI KB2536275 http://support.microsoft.com/kb/2536275 -- SYS KB2764302 http://support.microsoft.com/kb/2764302 -- NTFS KB2619234* http://support.microsoft.com/kb/2619234 -- RPCHTTP KB2724197 http://support.microsoft.com/kb/2724197 -- Kernel KB2732673 http://support.microsoft.com/kb/2732673 -- RDBSS KB2779069 http://support.microsoft.com/kb/2779069 -- CLUSSVC KB2699780* http://support.microsoft.com/kb/2699780 -- Registry
* Not updated from previous hotfix notification release
Lync Server 2010 Hotfixes Updates Resource Center for Lync - http://technet.microsoft.com/en-us/lync/gg131945
NOTE: If you cannot download the hotfix from the KB, then first, determine if you really need that hotfix and if so, consider contacting MSFT support for that build or look for another, related hotfix with similar files and build.
Have Fun... Doug