Russell has an interesting piece on P2P and mobile. I'm not entirely sure how relevant "file-sharing" is to mobile devices - after all, who cares about files, it's just "my stuff": music, contacts, calendar entries, video clips, and so forth. Isn't file-sharing predicated on the concept of files?
But that's just pedantic nit-picking on my part: we know that people want to share things with each other, and P2P is just an acronym for any number of technologies which enable this. I think the world of mobile might well prove easier for the music industry to exert control over than the fixed-line internet was, for a couple of reasons.
Firstly there are a small number of "choke points" in the networks, at the operators themselves - and many players in the music industry already have relationships in place with these operators. If a "mobile napster" emerges then it'll be easier to block usage of it,
Secondly, the platforms are more tightly controlled: handset hardware and operating systems are tightly bound together. Except for a very few cases, you can't reinstall a new operating system onto a device, or mess too deeply with the one that's on there. This provides a little more control over what happens to content once it's on the device, whether that be through simple "forward lock" schemes or more sophisticated DRM snake-oil. This is, IMHO, once reason why Apple have been able to get iTunes out there with a reasonable amount of support from the music industry: they control the hardware, the OS, and the store, and that control helps them give record labels a warm fuzzy feeling.
Talking of iTunes, Russell quotes Jon Davis of BMG in his post. Jon was a client of ours when I worked at Good Technology and he was at Perfecto Records; one of my first responsibilities at GT was updating and revamping the Perfecto web-site for him. More recently, the first ever project that Future Platforms undertook was for Jon when he was at iCrunch, an online music service which I was involved with in the early days. One of the things we were doing with iCrunch was persuading smaller record labels to license their content to us to be sold online for 99p/track; so whilst I don't believe you can (or should) stop people creating their own ringtones, I have to recognise that Jon's spent more effort than most of us on both sides of the fence, trying to drag the music industry into the 21st century.
And to complete my Sunday afternoon ramble, isn't it weird how the massive successes of both the music industry and the telecomms industry in recent years (ringtones and SMS respectively) have been things they didn't anticipate, revenue streams their customers discovered for them?