Apple has filed a patent for "Remote access to advanced playlist features of a media player."
The following explains the function of the patented idea:
A media player can have advanced-playlist creation capabilities such as the ability to automatically generate a playlist around a "seed" song selected by a user. In some embodiments, the accessory can determine whether the media player can use a particular song as a seed song for an advanced playlist and can so inform the user. The user can then operate the accessory's user interface to create an advanced playlist based on a particular song, rather than having to interact directly with the media player.
It sounds a lot like Apple's Genius Playlist:
Just select a song, click the Genius button, and iTunes makes a playlist of songs from your library that go great together. You decide how many songs appear in your Genius playlist ‚Äî 25, 50, or 100. Refresh your Genius playlist to get new songs. Or save your Genius playlist so you always have it.
It's not unusual to try to patent a feature like this one.