MobileMe News:

The promise boils down to this: whenever you go to your inbox and other folders, no matter from where, things will be exactly as you last left them, no matter from where.

When Gmail started offering IMAP access, I switched from POP3 immediately. Obviously, IMAP is perfect if you want to keep the same hierarchy of mailboxes and messages on more than one device. But even if you only ever read and write mail from one computer, IMAP serves as an online backup. If the hard drive in your computer were to go bad, you won’t lose any of your mail, because it’s all on the server.