Tommorow is the Big Day for GNU/Linux, when Ubuntu goes through it's regularly 6 month upgrade. Ubuntu 9.04, codenamed "Jaunty Jackalope" is due for release. The consequence is, these servers will get slammed, meaning that's it's difficult for people who use other distributions on some mirrors to update their distribution. As a result, rather than hit the servers with FTP or HTTP, it would make sense to pull as much strain off the big iron as possible. There are many ways to pull this off, such as rsync, jigdo and bittorrent.
Unfortunately, as efficient as they can be, rsync and jigdo still hit the servers, even if it's light. Bittorrent doesn't have to, being a peer-to-peer technology. So, when you're looking to get your latest ISO downloaded and burned, so you can hand them out at release parties, install on new boxen, or just for archival, it would be best if you used bittorrent. Of course, if you use bittorrent, then rather than cut the connection when you're done, get at least a one-to-one ratio on uploads to downloads, so everyone can benefit.
Many popular bittorrent clients exist as Free Software for GNU/Linux, such as Transmission, GNOME Bit Torrent and rTorrent (text-based). Trackers will be ready, if they're not already, and the ISOs will be ready to go. Just find a link with a torrent to grab, and start downloading and sharing. No worries either for data speeds. Everytime I've used bittorrent on the release day, my connection was always filled to the max at 1 MB/s. Let us not forget how popular Ubuntu really is!
See you on the other side!
P.S.: The Ubuntu help documentation has a good guide for upgrading from 8.10, if you go that route. https://help.ubuntu.com/community/JauntyUpgrades