Mapping WiFi access seems to be a popular pasttime. There's a current Washington Post article summarizing all the web sites offering this info,
Getting Connected With the Hot Spots.
They like
www.wifimaps.com for the map details, (but check out the other sites they list also). Wifimaps.com even listed several points in some small towns deep in the mountains of northern Pennsylvania (Williamsport and Coudersport).