I was wondering about how to go about this same issue, tracking and reporting GPS on the net.
One of the things I was looking at was Data Services from cell phone carriers, EVDO in particular, Mind you, in Canada the rates are sky high, with Telus $15 per megabyte and $100 unlimited. Though it is restricted to digital coverage areas only, this would potentially cover you for internet access on major routes.
EVDO might be a bit much for reporting GPS on the net, but heck, you could even stream music from internet radio if you wanted.
I'm thinking the other solutions require a wifi connection.... of course free wifi access points aren't everywhere!