Delta Airlines are launching the Gogo inflight Internet service on their US internal flights. It can only work on internal flights as Aircell (who run the network) used a ground based transmission network. The system acts as an inflight WiFi hotspot.
VPN corporate access is allowed, but VoIP services are blocked (which probably means the VoIP block can be got around using a VPN tunnel – though FCC regulations don’t allow it).
The service costs a fixed fee of $9.95 for flights under 3 hours and $12.95 for flights over 3 hours. Though Delta are offering a promotion from Dec 16th through 31st where it’s free.
Planes have to be above 10,000 ft before the FCC allow operation.
Other airlines using Gogo are Virgin America, American Airlines and shortly Air Canada.