The September Cumulative Update (CU) for DST contains three changes :

 For US Eastern Standard time (UTC -5:00, Indiana East), the CU adds DST support and updates history from 2006 through 2009 to reflect the change in which DST is applicable for the whole state and not per-county.  Specifically, for 2005 and earlier, this timezone does not have DST.  For 2006 and beyond, this time zone now contains DST. 

 For the Middle East standard time, (UTC +2:00 Beirut), the September CU fixes the ambiguity in the DST end-date transition time.  It was the last Sunday in October at 00:00:00:000.  Now its the last Saturday in October at 23:59:59:999.

For the Namibia standard timezone, the September CU updates the display name to reflect that this is a UTC +1:00 timezone, and not a UTC +2:00 timezone.  However, the underlying DST rules and start/end dates have not changed.  We are investigating a request to modify those in  a future CU.

  For more information, see the following KB article :  http://support.microsoft.com/kb/2158563