Microsoft's Surface Sphere operates a lot like the original Surface, utilizing a projector surrounded by a ring of IR cameras, which is then covered by a semi-opaque globe. The IR cameras detect when the beams are being blocked, and transmits it as contact. Using it, I found there are still a few early glitches, but this is an amazing piece of technology and far along for a prototype.
Admittedly, this is a very early, and very rough demo, but the use of IR technology means that navigating the Sphere isn't quite as smooth or intuitive as a multi-touch display. Similar to the HP Touchsmart, I noticed that contact with the sphere had to be deliberate to get an accurate response. And one notable hurdle the Surface Sphere will have to overcome is light sensitivity. Flash photography affected the input mechanism, tricking the computer into thinking a giant hand was touching it.
Similar to the original Surface, photos and video tiles can be shuffled around the Sphere. The coolest demo was by far the Pong-style game, where blockades could be placed on the globe spontaneously using your hand or a Post-it note. There was also a neat demo where you could flick the sphere like a globe to make it simulate rotation, then drag your fingers across to create a paint trail. This has the potential to be pretty awesome.
The big question is why a sphere when so many of us are looking for a more practical application for a surface table, not a less practical one? Walking around to use a UI could be complicated and annoying for the average PC user. Researchers said the sphere was the most challenging surface possible, and if they could get Surface-style multi-touch working on that, they could get it working on anything. Maybe they could use it to model Trident data on a touch globe. They also said that academics could make good use of it, and I agree that I can see this being useful for classroom collaboration. The obvious uses are in public and retail spaces, for advertising and marketing. And a fun implementation is that it could be used for multiplayer gaming, because you can't see the whole sphere at once.