Apple Insider has an article about a new Apple (AAPL) patent filing regarding iPhones accessing iTunes libraries from anywhere. The gist is that your desktop PC can have all your media (songs, videos, Podcasts, and more) on it, and your phone would be able to download and play anything from your desktop PC.
This would be a huge bonus for Replay A/V users. Imagine having your favorite radio shows recorded on a PC at home, imported to iTunes automatically, and available for listening wherever you are. This can be done now with the YouSendIt plug-in we provide (as you can email yourself recorded files automatically), but this mechanism would be much slicker.
Go Apple!