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United has installed the service on their p.s. fleet (JFK-LAX/SFO). They have not announced plans to expand past that AFAIK.
I haven't heard of AC adding service and they have some limitations in that Aircell's gogo service won't work in Canada right now. I do believe that Row44 has clearance to operate in Canada so that should be an possibility.
Beyond that, the only long-haul international carrier currently committed to offering internet service is Lufthansa. They expect to have a demo plane flying this year and 50 equipped by the end of 2010.