If you'd like to understand how important network access is on a moving railway car, attend Train Communications Systems 2006: While this is a highly specialized event--taking place June 7 and 8, 2006, in London--it shows the tremendous scope of interest in the area. It's not just a few commuter trains and a handful of long-haul trains at stake here, but rather a radical rethinking of the role of telecommunications in rail businesses.
The first day is a workshop, with more a focus on information technology and telecom issues for rail operators managing their train lines. The second day has a greater number of speakers and panels and turns the attention on providing Internet service, looking at the whys and hows. The two days together cost £1350.