Syncing setup is brainless and painless - there's a new preference section in Entourage in which you can individually enable syncing with iCal, Address Book and/or Notes through .Mac. Simple enough. A little while after I checked those options, the .Mac syncing engine offered a dialog asking if I would like to merge items between Entourage and Apple's apps, or if I would like to overwrite Entourage. I chose to overwrite, since I didn't have info in Entourage's database and I was simply curious about the app.
Somehow, some way, even though I told the engine to overwrite Entourage, my Address Book magically increased to 499 contacts after the first sync operation. Maybe it picked up all those extra friends from MySpace or something during the sync, because last I checked I only had 326 contacts in Address Book. Upon investigation, some of my contacts had split into separate cards, with information either duplicated or obliterated. Even better: I am subscribed to my fiancé's Address Book (with editing rights) through .Mac, as we're helping to keep each other's contacts up to date in preparation for sending out invitations. The Entourage sync not only mangled a seemingly random collection of her contacts, but it blew away all of her groups.
Now before you fire off a snarling comment: yes, we have backups. I've turned into quite the backup nazi - but this post is more of a complaint and a warning about this new Entourage feature. Who knows if the mishap was the result of a .Mac syncing error or bug, but - call me biased if you gotta - I have a sneaking suspicion this had to do with an Office update that wasn't quite finished. I've never had an issue syncing anything else through .Mac, and that includes a lot of 3rd party stuff like Yojimbo, SOHO Notes and Transmit favorites.
So, boys and girls, the moral of the story is a classic: back your stuff up - and often (sub-moral: don't trust Microsoft, even if it is software from their Mac Business Unit).