is a brand new service from Apple that will soon replace, and supplant, .Mac. Apple bills it as 'Exchange for the rest of us,' meaning that it offers you one central place ('the cloud,' as Apple is calling it) to store your email, calendar, and address book. You even have a number of different tools that let various devices sync that data. Confused? Worry not! Apple has just posted a guided tour of MobileMe
that will give you a good idea of what to expect.