> I'm assuming that public wifi has session-specific encryption keys. That's false for open wifi networks. Remember Firesheep? Just fire it up at your local co

> I'm assuming that public wifi has session-specific encryption keys. That's false for open wifi networks. Remember Firesheep? Just fire it up at your local coffeeshop and off you go. Even for more secure public wifi like WPA2, vast majority of coffeeshops still don't change the default router admin passwords so you can take over it easily and listen in on all the traffic. Further, it's not hard for some rando to setup a safe-looking access point and get people to connect to it. Camp out near an office with a router, I'm sure you'd get plenty of hits. There's no shortage of attack vectors with no warrants required.