There are two implementations I would suggest for this - 1 is a business implementation, and one is technical.

1) Business
By teaming up with some huge data powerhouses (I'm thinking Google here, but Akamai or some other distributed cache/mirror company should work), the new releases would be able to be downloaded at full speed at the highest peak of demand. Hopefully this demand is only going to raise, but the past 2 major releases have been near impossible to download for the first couple of days and the first couple of weeks in the case of the ca.ubuntu repos.
In exchange there could be some reciprocal arrangement to perhaps offer Google services in a more visible manner, or some similar arrangement.

2) Technical
Integrate Bittorrent into the update process.
Although this would no doubt be a huge programming job, especially where data integrity etc. is such a huge issue, it would be a much more viable long-term plan that would also not force Canonical into deals that may compromise the integrity of Ubuntu's goals.
I realise that we can download ISOs to achieve similar results, but a seamless torrent-enabled update process would massively improve the user experience at launch times, and the ability to also upload would bring warm fuzzy feelings to the user base who believe in Ubuntu's aims.