I do run a Scalix Gropuware server, not a genuine Exchange server. My Nokia E71 MfE just works like a charm with it.

Not so the N900...
Ok here's my experiences after updating to PR1.1:

After updating I configured MfE and clicked on OK to start the first sync process. I decided to sync emails-only since I didn't want to mess up my contacts or calendar ;-)

Initializing server sync went ok and I caught myself staring at the email status bar for about 15 Minutes until all emails were pushed onto the phone. Sync showed status ok so after full-sync I closed MfE and openend Modest. What would you think? Not a single email there, all folders are empty!

Starting a manual sync afterwards will give me "Error in Exchange server" again. Bummer.

When trying to sync contacts & calendar the first sync also works flawless (and all entries are even shown in calendar or address book) but the 2nd sync will bring up the same o' error message...