Hello everybody,
Just as a reminder, after upgrading to Exchange SP1 on a SBS2003 machine, ActiveSync does not sync anymore calendar (contacts and messages are fine), when sync is done with the server (still works however if sync is done with the partner PC).
The problem has been looged to Microsoft support. It has been escalated up to the dev team. They came out with a hotfix. It is only available thru Microsoft support channel, the magic reference is : KB892234. It will be released with Exchange SP2.