Interesting. I think it would be nice to see every payphone turned into a wifi hotspot wired into a city wide network. This serves two things: 1) City wide wifi (Don't we all want that?) 2)Payphones are then just VOIP handsets with a payment machine attached. Win-Win<p>Payphone fees could probably be reduced but maybe not. Maybe the money collected from the payphones is used to (partially?) offset the costs of running the city wide network.
In case you didn't see the funny skit introducing this at this month's NY Tech Meetup: <a href="http://www.youtube.com/watch?v=eJx91LDXREk" rel="nofollow">http://www.youtube.com/watch?v=eJx91LDXREk</a>
A great payphone hack would be to make it a dead-drop. Ie: put in a hard drive and a usb port and small controller. Then plug in your usb key, dial a number, it gets copied to the HD. Next person to insert his key and dial your number gets the data you copied.