Here's a good metalink overview:
(http://www.downloadsquad.com/2006/08...ftp-downloads/)Metalink makes complex download pages obsolete by replacing long lists of download mirrors and BitTorrent trackers with a single .metalink file. As you might have already guessed, a .metalink file is a file that tells a download manager all the different ways it can download a file. The file itself takes the form of an open XML standard that can list an unlimited number of HTTP and FTP sources as well as BitTorrent trackers and ed2k and magnet links.
It usually results in really fast and automatically verified downloads.
If you want to download ubuntu iso from multiple mirrors at once, you can use bittorrent.
keep it simple.
BitTorrent uses multiple PEERS at once. This is great and uses users bandwidth. But, not all places allow BT downloads. Sometimes they're blocked.
Metalink allows you to use whatever is available, whether it is BitTorrent, ed2k, magnet links, or mirror (http/ftp) servers.
this is wicked. Everyone says 'use bittorrent for downloading isos.' I would if my isp didnt packetshape torrent traffic to death. Thanks!