Can can with success use .torrent files for downloading the final version of Ubuntu 9.10. This way you can download the latest image without affecting the main server or any of the mirrors.
You can also use zsync to save your bandwidth and time while you download the final version of the karmic koala.
zsync is a file transfer program similar to rsync. zsync is optimized for distribution of files across Internet, with one file on a server to be distributed to thousands of down loaders.
zsync -i yourexisting.iso http://final.iso.zsync
If you haven't got zsync installed, just type:
sudo apt-get install zsync
Happy downloading and congrats to everyone that has contributed to the Karmic Koala release, including everybody in GNOME, KDE, Xorg, Ubuntu and Canonical!.
Read the official release announcement here: https://lists.ubuntu.com/archives/ubuntu-announce/2009-October/000127.html