Spaceway 3 is the only one they are using. They have the option for 4 if the service takes off like they are planing. They say they can support over 1000000 remotes on the bird.
That's right... S1 and S2 were hijacked for DirecTV but Hughes was allowed to play with either S1 or S2 (don't remember) for KA broadband testing. Totally forgot about the S3.