Most modern stadiums are moving that direction -- http://arstechnica.com/information-technology/2013/03/the-49...
It'll be another 3 years before things are really ironed out in the newer buildings. Not sure how older ones will manage to deal with the situation.
Cisco is helping improve the situation as well although it is expensive as was noted earlier. http://www.cisco.com/web/strategy/sports/stadium_wifi.html
love the line "put real fans in the best seats".