Personally I think Sirius is an investment like Vonage. Cell phones were already advanced beyond Vonage, and with the new unlimited mobile calling plans Vonage is doubly screwed. Sirius must contend with the fact that everyone in the U.S. has two ipods, and if they only have one, they make sure and use it in the car, at home, and at the gym. I personally will never buy an Ipod and just bought my mom a creative zen stone for her birthday. But for example, my girlfriend has had an ipod integrated with her car stereo for two years and she has a second ipod that she uses for working out and to link to her home stereo.
2nd point to be made about Sirius not even having a market. The people who won't pay for an Ipod, like myself, are the same people who won't pay for radio when its free already. Sure there are ads but there are also tons of stations. Sure, there is no talk radio, but these same people not spending money on ipods or sirius radio are the ones who have learned to get by without frills like that.
Disclosure: I bought Sirius and sold on the good news, when the merger approved. I felt lucky to get out about even. The stock has gone down and then nowhere since.