The invention of this type of locomotion has been made in 1987 by a Japanese robotics researcher Kazuo Yamafuji. It has been patented in Japan 1996.
The author of the Elektor Wheelie is Christof Krohne. He has started 2008 the ZZAAG Project and offers components in his shop. Roberto launched a similar project. Even earlier was the open-source forum called into life. The roots of the open source "mobility-help" are probably on Trevor Blackwell and the MIT. Basics on balancing you find on this site.There is also one entirely without electronics ;-)