Foisting off multiple formats

Let me pose a question: how many different times can you sell someone a piece of media that will play on a single device?

Back when we all had Sony Walkmen, we bought cassette tapes to play in them. When the Discman arrived, we bought CDs. With VCRs, we bought videotapes. With DVD players, we bought DVDs. Consumers have never really balked at purchasing media on a new format when that format offered advantages over a previous format - even if they already owned a particular movie or album, they'd buy a second copy.

There was an interesting side note in David Pogue's review of the Motorola ROKR phone today:

"No, you can't use songs as ring tones, at least not the songs you've bought from Apple's music store. (You can use ordinary MP3 files as ring tones, but loading them onto the phone isn't trivial.) This, too, is almost certainly a limitation driven by corporate interests. Cellphone carriers charge $1.50 to $3 apiece for ring tones; Cingular certainly wouldn't want to hand that lucrative business over to Apple's music store."

Essentially, Cingular hopes you will buy a snippet of your favorite song from them to use as a ring tone, and buy it again from Apple to play on the same device. It's interesting to note that Apple charges less for the full song, at higher quality, than Cingular charges for a ring tone excerpt.

Will that stand? I'd like to think it won't, and that the answer to my opening question is one. But are there examples you can think of where it isn't?