There's a scouting system called
STAMP that was developed for this exact purpose in 2006; if you do a search, there are a fair number of threads about it.
Generally speaking, FIRST turns a blind eye to wireless LANs at competitions, seeing as they are pretty harmless (not to mention that the volunteer staff are way to busy to police that sort of thing). In the past, teams have run private wireless networks as well as networks open to other teams (STAMP, Sundial, etc.).