Yes, that's interesting and thanks for the link. Unfortunately, with the Shuffle still only 1Gb, it's still not going to be as useful as I hoped. (I might still get one though)
Just think of what Apple could do if they designed something like this, but all in one piece. They could make it sleeker, but still have double the battery space of the Shuffle. 4Gb cordless headphones with built in player and 24 hour battery would be easily doable and exactly what I'm looking for. Sound would be way better than is possible with earbuds too.