I wondered about that , too.
I suspect the topic will become more involved, regarding bittorrent, though.
I see more and more of the linux distributions going that way in order to save bandwidth on the server's side. Doesn't help the downloader from what I gather.
Some legitamacy to it, but I get the impression it's mostly being used otherwise
Myself, I don't want to use that type of transfer because of noted security problems with accepting files from unknown sources.
I just realized yesterday, Mandriva (Mandrake) seems to be going the bittorrent way.