I have had a few questions come in late last week about some CRM 2011 Outlook clients being on version 5.0.9688.1544 instead of the most recent Update Rollup 5 version 5.0.9688.1533. The reason for this is that on new installs of the CRM Outlook clients we check for Windows Updates and last week Tuesday (12/13/11) we released a hotfix outside of our standard Update Rollup process. This was a proactive fix to help certain CRM Outlook clients who had connectivity issues while configuring to be able to configure correctly. So, if you have had a user complete a new install, or if an existing CRM user has their computer set to automatically download and install Windows Updates, they may have had this pushed down to them as we published this as an Important Windows Update.
Complete details can be found in the KB: Error message when you try to configure the Microsoft Dynamics CRM Client for Outlook: "The LDAP server is unavailable" - http://support.microsoft.com/kb/2645912
There are no known issues running your CRM Outlook client on version .1544 while your server is on .1533 or earlier versions.
There is also no reason to push this hotfix out to your clients unless they are running into the issue described in the KB above. This proactive hotfix will be included in Update Rollup 6 when that is released in the January timeframe.