»Safety in numbers

On the hourlong trip from Mountain View to San Francisco yesterday evening, I was multi-tasking: using an AT&T GPRS modem (in the form of a PCMCIA card), I was doing some work, while watching video clips from yesterday's breath-taking Tour de France time trial, and watching the fog roll over San Bruno Mountain.
A fellow sitting across from me started talking about Macs, and free wireless access points in San Francisco, and sent me a white paper from the Bay Area Wireless Research Network.