This from Wired
Yesterday, TorrentFreak alerted [wired] to a new BitTorrent client with a "selfish" anti-social streak. BitTyrant, a project of the University of Washington’s computer science department, is based on the code for Azureus 2.5. So, it’s a cross-platform Java application — that’s good. What makes BitTyrant bad is that prioritizes your upload connections, favoring the peers that provide the best download speeds. You end up sharing more of the torrent with only the peers that give you the biggest chunks. The slower peers that aren’t giving you as much data are choked and relegated to the bottom of the list.