I found out today that our buddy, SBS 2003 without Service Pack 1, is being removed from the list of supported products today. Not to be confused with SBS 2003 with SP1, or SBS 2003 R2, which continue on for support.
This means that today is a great day to Upgrade to SBS 2003 Service Pack 1! It's free!
The full list of other products that will no longer be supported, and when is available on the Lifecycle Support Page.