Mike Davidson, who is the CEO of Newsvine and half the brains behind the sIFR web typography project, has written a useful guide to getting Gmail to work with an IMAP account.

You cannot access a Gmail account directly over IMAP as you can with POP, but you can—as Mike describes—set your Gmail account up to auto-forward mail into a dedicated IMAP account.

As a result, he says:

Since Gmail’s auto-forwarding feature leaves headers for the most part intact, I can now receive fully synched, fully intact copies of all my Gmail messages to any computer I happen to be on.

The best of both worlds.