PS: Just a thought: doesnt the Karnivore system from CIA scans for these frequencies?
Carnivore was an e-mail scanning system.
American electronic signals intelligence in space is operated by the National Reconnaissance Office. Their satellites, currently the MENTOR series, are extremely capable of detecting and recording radio traffic.
However, if the only transmissions sent from the aircraft were the ACARS bulletins already received in Paris, which seems probable, that would mean the satellite would not be able to provide any new information.