In the UK the trains had free wiki which was fab - made going to London productive. Found out last night that they are now charging for it - cue grinding of teeth and endless rage.
That said, you can pick up mobile broadband packages for around $10/month here with 1GB usage which should have coverage for most journeys in to London.
east coast used to be free wifi, I think virgin charge? and crosscountry dont have it at all. damnit now I want this service for uk trains.