I’ve been waiting for this news since Gmail was first launched: Gmail now provides IMAP access. Not all Gmail accounts have this feature turned on yet. My regular Gmail account does not, but my Google Apps for Domains account does. I would have been willing to upgrade to the Premier Edition at $50 per year per account to get this, but I’ll take it for free as well :-)
Looks like downloadsquad was the first to report this.
I’m off to go try it out with a few email clients and see how it goes.
Another helpful link: How do actions sync in IMAP.