What SAS has said: (press release from October 2010)
"We are currently negotiating with a number of service providers and aim to offer our premium customers free internet onboard our flights, starting already in April next year."
And:
"SAS' Boeing 737s will be the first to have in-flight connectivity installed, and initially offered on Norwegian domestic routes, and from Oslo and Stockholm to London, Frankfurt and Paris. In the first phase, nine B737s will offer the service, followed by short-haul and long-haul aircraft."