Kurt Shintaku's Blog

It looks like this patch is a little more than what it describes:
http://www.microsoft.com/downloads/details.aspx?FamilyID=a8c26743-5a77-4947-aad4-6a6b8ef84f9c&DisplayLang=en

Apparently, this patch for Office Communicator 2005 also fixes some potential issues when integrating with Outlook 2003/2007 to provide "presence" information about users that have sent you email.

Some folks have reported that this fix essentially fixed some Outlook hangs that used to be a result of using Office Communicator 2005.