Popular Science shows you how to equip a solar-powered backpack as a roving cellular-to-Wi-Fi hotspot: Mike Outmesguine of The Wireless Weblog filed this How2.0 article for Popular Science on using Seattle-based Junxion's portable cellular-to-Wi-Fi/Ethernet gateway with a backpack and a solar charging system. The total cost is about $1,100, but you could be the best friend of every other commuter or game player near you.
A lower-tech but similar solution has been pursued by Seattlite Casey Halverson the Seattle-to-Tacoma Sounder commuter train. You have to be in range of Casey for it to work.
Very cool! I wonder whether these were inspired by wi-fi visionary Julian Bleecker's wifi.Bedouin: