PLC?
Couldn't they try a PLC connection as well?
Thalys will introduce broadband internet access to passengers travelling between Paris, Brussels, Amsterdam and Cologne by 2008, the company announced today. It will be the first international high-speed train to provide this service across European borders. Thalys has selected Nokia Siemens Networks, UK based 21Net and …
No doubt it will get priced so highly its hardly worth bothering with.
Why don't they just make it ludicrously cheap (eg £2 per journey/ or in with the ticket) and block all incoming ports (unless 'related' or 'existing') and only allow outgoing ports 80, 443 with a local DNS?
At present a lot of these public wifi hotspots have port 53 open anywhere to allow use of a public dns server - but this means you can just tunnel an SSH session over it without having to pay for the connnection! This is silly!
...for Lufthansa's trans-Atlantic in-air WiFi, which was tragically ended in 2006. It was not perfect, but made being stuck in economy class for 10 hours a little less painful, which was worth the extra ticket cost over flying United (well, that and the drinks and somewhat improved vegetarian food).
It seems like 10 USD/EUR is about the impluse-buy point on net access for trips over 2 hours, and would make me more likely to choose to ride DB/Thalys over flying one of the many cheap airlines with whatever food I can grab in the terminal.