I believe it helps because I've been reading many times people where giving up Bitcoin-Qt because it takes too much disk space, and it's slow to start. They switch to "light" clients, so it's good news to hear of one person choosing to help the network. My understanding is that there can't be too many nodes.
It takes nearly a week to sync, but once done, there is really no problem for Bitcoin-Qt.
Supposing every 12 hours, a reference blockchain was put up on bittorrent.
Then new clients could grab the reference from bittorrent and typically be under 12 hours behind.
Would that speed it up?
If the reference was kept separate from what was updated by client, then every time a new reference block was created (every 12 hours) every client would quickly update since the torrent would just need to grab the new bits.