Hi Mike,
this is an Airbus A340/300, the system used is called Boeing Connexion system. This service should be standard on the new Boeing 778 (or was it 787?).
They have several access points inside the plane for Wlan access. Apparently the 2.4 GHz frequence used by Wlan doesn't harm the plane's electronic systems.
I'm sure that you can find more about this on Google.
I just turned on my laptop and had to enter the access data into the client of my Wlan adapter. A registration login screen appears and you have to register to be able to use this service. And of course you need a valid credit card.
Official price is 30 US$ for the whole flight (flat-rate) but surprisingly, I was charged only 20 US$ (introductory offer?). Not bad for a 10 hour flight and unlimited broadband access.
The flight carrier is Lufthansa, it is my understanding that all their US-Germany flights are now equipped with in-flight internet access. This is LIVE access with full 5 MBit (of course for the whole plane but not many people are using it). It is also my understanding that there is a 20-30 minute satellite reception gap when there is no internet access and also two gaps of several minutes when the service changes between two different satellites.
I just love it, it makes the flight time pass away like nothing.