you absolutely need an active subscription. You cant get sirius without it.. the thing is, even though they have an internet player, it is all flash, so you can play it through your iphone.. also, the iphone app for sirius seems to be awesome as far as the UI and organization.
I also have to say, sirius is WAY better than XM, but i am glad that they merged.. Its a good thing.
I still chuckle when I think about all the hearings about the "monopoly" the merger would have. There are a billion media companies out there that have more media pull than Sirius XM will have (Clear Channel, anyone?). Yet some stupid group of people decided to put that whole thing off when it was obvious to most of us that there wasn't really the demand for 2 satellite radio companies. The $13/month (or however much it is) is why I haven't signed up.
I'm hoping an iPhone app might allow them to offer cheaper packages, but I doubt they will. I would love to get football broadcasts, but I just use my iPod for most of my music.