Ubuntu Package Torrent - Seeding package with torrent transparently to users

I have this idea: why not automagically retrieve list of packages update from the central server and the packages itself from other users that have this .deb package already on their pc? I think that this could aid Canonical's servers and create a more strict sense of community. This could simply be done by using well known torrent technology - widely used every day - to pre-download packages that the user will install during an upgrade, or an install. If few people have that specific package, rollback to http download or download from "Canonical" torrent seeder could be done, so no difference is seen by the end user..
Every user could setup how many bandwidth ecc.. the system could use, and all will be happy!