iPod Touch and GoGo
 

Looking at GoGo's plans, does the iPod Touch qualify for the Mobile Pass, or does it need the Flight Pass?

It's a mobile device, so the cheaper rates apply (gogo mobile pass).

Haven't used GoGo or researched at all yet, but how does the system tell what kind of device you log in with? E.g. what prevents someone from paying the rate for a mobile device, but then logging in with a laptop?

Pretty sure that it checks your browser's user agent, that is, what it identifies itself as. I personally have not tried playing with the user agent on a flight, though I'm sure others have. :) I imagine you could trick the system into thinking your laptop is a mobile phone or achieve the same result by tethering into the mobile device.
Not really cost effective compared to the monthly passes if you use the service that much.