I think Paxboy is correct - the sort answer is no one really knows.
My understanding is WiFi and Bluetooth use the same frequency range (2.4Ghz) but with different power levels, hence Bluetooth has a nominal range of around 10m whilst WiFi is allegedly up to around 300m.
Mobile phones tend to have a range much higher than this and hence transmit at a higher power - also there is a problem for the mobile phone networks as the whole principle is based upon the phone only seeing one or two basestations - when it is at several thousand feet it can see a lot more and the network can get horribly confused.
Also I had heard in the past that some mobile phone frequencies are very close to aircraft navigation frequencies - I really ought to know this - typically 900Mhz. The only thing I could think of for this would be a localiser - perhaps someone could correct me?
I think connexion does use WiFi - the LH trial is using approved laptops but I read somewhere that you would be able to get your own laptop "approved" for use on the system in the future which would suggest it is using normal WiFi?
Very confusing!
TZ