Just the Tour for now. Haven't heard any word if it'll be released for other devices. I imagine it would be, or would assume so, but haven't seen or heard anything about it on other devices.
http://images.blackberryos.com/misc/PTTonBBPromo.pdf Well I found this floating around out there and it says compatible Blackberry Smartphones. Thats why this question of more BBs getting PTT came about