At CTIA Wireless 2007 keynote Microsoft's Peter Knook announced that Cingular aka "the new AT&T" will provide free updates to new and existing customers to three of their Windows Mobile Devices from Windows Mobile 5 to Windows Mobile 6. The devices that will be getting the free update will be 3 of their newer and popular devices: the Samsung Blackjack, Cingular 8525, and the Palm Treo 750. Palm made their offical announcement here.
The update will be a downloadable update (you will need to flash your device) with a projected date of availability being around 2H of 2007. All new devices sold after proper testing is performed will ship with Windows Mobile 6. So if you were waiting on which devices will be supported this may make your decision making process a bit easier. For more CTIA 2007 coverage and pictures of some nice phones and devices revealed be sure to check out the blogs provided by Jason Dunn here and Chris Leckness here.