Segway obviously brought the two-wheel mojo, and seems responsible for most of what's being shown at the moment. As opposed to the Segway's tilt-and-cringe system of navigation, the P.U.M.A. has a more regular steering wheel, but while they're currently demonstrating it with Segway-style acceleration, they plan on swapping that for "Nintendo-style" buttons behind the wheel for acceleration and braking. For GM's part, they plan to integrate its "connected vehicles" technologies to improve safety and efficiency -- and we might not see P.U.M.A. on the road until they can pull it off. The car will not only communicate with other cars and with GPS, but will sense and stop for pedestrians. They plan to show a connected version that will be available for test drives by Real Actual Humans this coming fall, and then next year will come the scariest of all unveilings: GM styling. Right now this is just a chassis, GM plans on slapping on all sorts of "fashionable" candy shells, and if the incredibly unrealistic and "futuristic" renders we saw are any indication (see the gallery below), we'd really rather do without.
The biggest obstacle to commercialization, however, is the lack of infrastructure: P.U.M.A. in its current incarnation is designed for for bike lanes, and the first cities to get it will be ones with existing, comprehensive bike lanes -- not as much of an obstacle in Europe, but quite the stretch for most American cities. Still, the mathematics are quite alluring, with a 35 mile range at 35 mph for a 35 cent charge -- even us mouth-breathing Statesiders can understand that.
Update: We added a video after the break, along with a couple outdoor shots in the gallery. The thing really does look and operate like a two-person, sit-down, Woz-free Segway. You have been warned.