Wife & I flew AA SFO->JFK 767-200 w/gogo. If you want to share it's easy - I logged in, did my business and logged off. Logged her computer in, she could browse, I watched a movie. I have the monthly subscription, I log in on my laptop and my Incredible all the time - just not simultaneously.

Relative to setting up a hotspot, I think not only gogo but also the airline and FAA would probably frown on that. Best bet would be a crossover RJ-45 cable.