Seems like it's illegal to use in California: http://www.dmv.ca.gov/pubs/vctop/d11/vc21968.htm
http://en.wikipedia.org/wiki/Electric_bicycle_laws#Californi...
http://www.leg.state.fl.us/statutes/index.cfm?App_mode=Displ... section (83) seems to have been added specifically to make Segways legal, so perhaps someone with the resources for lobbying and/or a court battle could make these boards legal.