So MS’ Surface Computing uses a rear projection/sensing system which has high sensing resolution but is bulky and expensive. MS’ MultiTouch uses tiny, rear-mounted infrared transceivers, offering a more compact (and cheaper?) setup than Surface but with lower resolution.

I wonder what the pros and cons of these technologies are compared to the iPhone’s use of capacitive sensing technology?

I can see that Microsoft’s methods would allow the use of a stylus or gloved finger, whereas the iPhone will not. And Microsoft’s methods (presumably) work with a hard glass surface, so you don’t have the fragility or limited lifespan of a resistive touch screen’s soft plastic (polyster) surface.

But I don’t think that support for non-conductive input devices (gloved finger/stylus) alone necessarily justify the cost and complexity of these over the iPhone’s technology, so I’m curious if there are other advantages to these.