"To date, Aircell and its carrier partners have not identified any network security vulnerabilities in the Gogo Inflight Internet service that are threats to our customers. Credit card transactions to access Gogo are encrypted and fully secure. Other Internet traffic on the Gogo network is as secure as any public Wi-Fi hotspot in a hotel, airport or coffee house. For users who wish a higher level of information security, Gogo supports virtually all VPN clients. Aircell is committed to our customers' safety and security both in the air and online and will do all we can to ensure our customers' information remains secure and private."
Fair enough, and well-taken. bMighty has talked often enough about the risks of public hotspots, and the advice we've offered stands: be careful (I'd say be wary!) of any public access service, on the ground or at 30,000 feet.
The point is wariness, to use that word again -- anyone connecting wirelessly via a public point needs to have solid guards up, and keep them up as long as they're online.
Whether the public access you're using is Gogo or not, if you're on the go, go VPN.