Many Flying J's have WiFi available. See http://www.tonservices.com/hisp_home.htm for pricing and http://www.tonservices.com/active_sites.htm for the locations. I've been on a trip (and I'm not a trucker, just driving in a passenger vehicle which happens to be a pickup) via I-15, I-80 and some other routes to Indiana and Ohio and returning mainly via I-70, I-44, I-40 and I-15 and have used the Flying J's to download MP3 files of a radio program I wanted to listen to.
http://www.truckstop.net/locations.asp has a list of current and planned WiFi hotspots, but they're clearly not as far along as Flying J is. As far as I can tell, TA Travel Centers and Pilot Travel Centers do not offer WiFi. Stan Slonkosky ( driving back to California today http://map.findu.com/ke6zc-1 )
