Two things are particularly interesting. First, Kamen has apparantly develped a gyroscope-like system that can keep any vehicle (scooter?) in a state of balance once in motion. Second, he has developed something known as a "Stirling" engine that while I don't have the expertise to really understand it, supposedly is a highly efficient motor that could be used for such a device. Maybe other more qualified Freepers could weigh in on this and fill in some details.
If the above is the case it could help explain the hype. Imagine a powered yet clean personal transportation device that was stable and safe and efficient enough for personal urban transport. This could truly change the ways cities are developed simply by realigning roads and such.
If anyone has more info on the announcement and where to view it on Monday please advise!