Since you've done a bit of engineering on this already...
What type of servos might you use to make something similar, but with more weight capacity? The intended pan/tilt would be able to support say, two or three pounds at least (Digital SLR + lens).. though the speed of seek to desired location need not be too fast. It'd be nice to put together an auto-panner, and also use it coupled to some IR sensors to do wildlife photography, for example, if it were something like fifty bucks to put together. I'm sure I'm far from the first to ask the question. Bugger of it is, if webcams used better sensors and optics, then you could use something like this to composite together gigapixel images from 640x480 shots stitched in software.. as it stands, the noise factor in webcam sensors makes it kinda pointless 