I had posted an article called Speeding up your Ubuntu updates on 7-Mar-2009. What I had failed to realise was the fact that Ubuntu updates are now hosted on a Malaysian site at the Multimedia University at archive.mmu.edu.my since 21-Jun-2008.
Jaunty users will see the Malaysian host when they run the Software Sources program in Ubuntu. Earlier distros will need to manually change the source in /etc/apt/source.list file. Go to this link for more details.