As of January 2009, the iBOT powered-wheelchair will be discontinued. This is unfortunate for the disabled community -- Dean Kamen and the others at DEKA (the same people responsible for the Segway and Luke Arm) developed an amazing robotic wheelchair that was (somewhat) unique it its ability to transition from a statically-stable, 4-wheel configuration to a dynamically-stable, 2-wheel configuration to give occupants added height. Further, by pivoting pairs of wheels, the wheelchair and occupant were able to dynamically balance while traversing stairs, not to mention the wheelchair's basic ability to traverse (relatively) poor terrain, such as sand and gravel! All of this was possible due to careful controllers and internal gyros (not entirely dissimilar to a Segway). Read further for discussion -- specifically about why this loss for the disabled community could be an opportunity in disguise for the robotics community and a big win for Kamen and company.
Update on June 20, 2016: According to recent reports, DEKA and Toyota are joining forces to revitalize the iBOT wheelchair. Details can be found here.