http://gaming.invisibill.net/wow/torrents/WoW-18.104.22.16851-to-22.214.171.12467-enUS-Win-patch.torrent is a link to the BitTorrent metadata for today’s 3.1.0 patch (enUS). Using this .torrent will cause you to pool with all users of the official Blizzard downloader, as opposed to pooling with only the users of a separate Torrent site’s users. For example, using a .torrent on TPB will cause you to pool only with other TPB users.
With this, you can use your own existing BitTorrent client to download the patch files directly from the Blizzard swarm. All the benefits of the BitTorrent protocol without the flaws of Blizzard’s downloader. No need to open a ton of ports that might be in use for other things or other PCs, just use your regular BitTorrent client’s settings.
If your BT client asks where to save it, choose C:\Program Files\World of Warcraft\Patches\ to have it use your existing pre-downloaded data. If you installed WoW in another location, you should obviously use that location instead of C:\Program Files\.
Note that with BitTorrent, your download speed is limited only by the total of everyone else’s upload speed. Downloading the patch from a hundred cable modems will be much faster than fighting a million people for a regular HTTP download off a single file server. The more people you have using BitTorrent, the faster it becomes (the exact opposite of regular file servers).
If you just want a fast, secure download, click on the link at the top and start sharing your bandwidth. If you’re interested in the technical info behind this (and some general BT tips), http://gaming.invisibill.net/wow/patcher.html is a page I made in 2005 explaining the issues with the Blizzard patcher. If you don’t know what BitTorrent is and don’t have a BT client installed, either read up and install one, or find another download method. =(
Disclaimer: I created this .torrent file containing metadata related to the WoW patch files. My file does not contain any parts of the patch itself or other Blizzard files.