So it's sort of like Microsoft Live Mesh, except it costs $100/year...
Over the years, two million people signed up for .Mac, according to Apple, even though it was a sort of motley, unfocused service.
MobileMe, however, has a much clearer mission that solves a much clearer problem. It’s meant to keep the e-mail, calendars, address books and Web bookmarks on all of your computers — Macs, Windows PCs, iPhones and iPod Touches — synchronized in real time.
It works by storing the master copy of all this information in the cloud. Whenever your machines are online, they connect to the mother ship and update themselves. When you edit an address on your iPhone, you’ll find the same change in Address Book (on your Mac) and Outlook (on your PC). If you send an e-mail reply from your PC at the office, you’ll find it in your Sent Mail folder on the Mac at home.