Which again misses the boat.
MobileMe is a next-generation .Mac, which also supported iDisk, and as it happens, iDisk is Apple's recommended way of backing up your data, prior to Leopard. It works by copying everything to Apple's server, where it can be fetched your other machine(s). Or, more to the point, various law-enforcement agencies with warrents (or, given the way things are going, probably without).
I've previously whinged about not using gMail for the same reason. It's bad enough having the UK government throwing privacy and civil liberties out the window, and losing our data in the process. I don't see any good reason for doing the same again, with the US government. It's just mad.
I really, really hope that Leopard's iDisk support can manage duplication without having the MobileMe or .Mac servers in the loop, but I doubt it.