Hmm. .Mac and MobileMe always worked for me, happily synching my contacts and calendars. There was a hiccup when it was transitioned from .Mac to MobileMe which was blamed on my use of the mac.com variant of my account name instead of me.com. Nevertheless, this was quickly resolved thanks to an Apple Executive Team intervention, it continues to Just Work.

All I need now is a small extension to Universal Control that would let some direct control be delegated to my AppleID and one of my devices, to temporarily control, for setup and short show+teach sessions, family iPhone and iPad devices in remote locations.