I've discussed panorama robots in the past, and here is a new creation. James Catan has created several Lego robots to do timelapse and and pan/tilt pictures. One of them were recently presented in Gadget Review, and shows holding a Canon Rebel XT with a kit lens. So not quite 5D, 200mm f2.8 as with Jeffrey Martin's rig. Yet still a good and simple setup.
Another interesting pan & tilt product comes from Sparkfun. It is a robot arm, consisting of servos and and a claw. It will definitely not hold a SLR, but possibly some smaller pocket cameras or phones. As far as I understand, the complete robot arm comes in several parts which you'll have to add to your order separately.