The UMTS-based service is designed for high-speed trains with cellular connections: The service, much like other rail offerings, puts Wi-Fi in carriages, and offloads Internet access via a cellular up-/downlink, in this case over UMTS. IPWireless says they surpassed one Mbps at 220 kilometers per hour; they expect 400 kph is an effective top limit.
Ah, to live anywhere near a country in which trains regularly travel at 220 kph, even!