It's a rule as old as time: tell a bunch of geeks they can't do something, and they will find a way. Any way. Thus the Flash-based Phweet trick to get around Aircell and American Airlines' ban on VoIP using their Gogo in-flight Wi-Fi service. Now, Aircell has responded with a light wrist-slapping statement.
It is against American's policy and Gogo's terms of service to use VoIP. Aircell has multiple protocols and practices in place to prevent the use of VoIP. Obviously, it is extremely difficult to stop every instance of VoIP but Aircell is monitoring and working constantly to enforce American's policy and Gogo's terms of service.
It's a pretty general piece of ass-covering, but I kind of agree. Just because you can, doesn't mean you should. Any shred of anything that helps preserve the sanity of the air-travelling populace, I'm all for it.