Update: Folks in the comments are mentioning that they're getting Tech Support Texts telling them to go grab the download, which should be up at 6pm EST Today. Still no word from the source I expected to get this information from, the Official Palm Blog

See this link - right here? It comes from AT&T's Windows Mobile Devices page:

Are you an existing Palm Treo 750 customer?
Download the latest Windows Mobile® 6 Professional software update for the Palm Treo 750 that updates the entire operating system from Windows Mobile® 5.0 to Windows Mobile® 6 Professional plus adds HSDPA support, AT&T Mall, AT&T Music, MEdia Net, CV (video) and many other updates and fixes. CAUTION: Firmware updates will DELETE ALL applications, data, and settings on the device. Back up all information on a PC or storage card before installing the firmware upgrade.

As in: the long-awaited, delayed-but-not-really (since-they-never-announced-a-date), everybody else got it first, already leaked anyway, dear god it's been a long time “in the queue,” insert-your-delayed-adjective here Windows Mobile 6 Update for the AT&T Treo 750 will be showing up today. Go ahead, try the link:

Download the AT&T Treo 750 Windows Mobile 6 update

Didn't work? Try it again. If it's up on the AT&T page, it should be showing up at Palm's site soon. Right? Pretty Please?

(Thanks to Roger and eddiejames for the tip!)