UK's Grand Central Railways chooses Icomera: The railway will equip all its carriages with onboard Internet service. Service will commence between Sunderland and London Kings Cross in Sept. 2007. Icomera is the world's largest operator of train-based Internet service. They cover dozens of trains in Britain's GNER line through a former joint venture (Icomera UK, which will handle Grand Central, too), and on the SJ line in Sweden. (Update: See comment--Icomera UK is now wholly owned by the Swedish parent firm.)
Despite rumors last year that the Dutch rail operator NS was preparing to deploy Wi-Fi access across its entire operations, there's been no motion on that front. A page from seemingly last year reports that the "draadloze internettoegang" (wireless Internet access) is in testing in 2006.