“The mobile devices can then wirelessly transmit data from one mobile device to the other”
This, I believe, is one of the reasons Steve Jobs wanted iTunes to move away from been forced supplying and maintain DRM files. So far they have been able (barely?) to keep the DRM model working, as long as a computer must to use to download music to the iPod. However if Apple want to put add in the functionality as detailed in the patent, one mobile device pretty much transmitting data ad-hoc to another mobile device, supporting the current DRM gets problematic fast. First they would have to spend time getting it to work, getting two client devices to maintain DRM would be more complicated than the current host/client situation that is used. Then, more than likely, it would be cracked which won’t be as easy to fix as updating iTunes is, which would make Apple look bad. The solution make sure that Apple start moving away before the iPhone is released, Jobs letter on music was one month after the iPhone was announced.
So while Steve Jobs as always is less than honest about his intentions as listed in his letter, this is probably another example of how he is way a head of the game and on the way to making pant loads of even more money.