Launchpad Entry: https://launchpad.net/distros/ubuntu/+spec/xdeltas
The dist-upgrader that was introduced for breezy->dapper upgrades relies heavily on being on a (fast) network. A process for (dist)upgrades without network should be added as well.
Not everyone has broadband network or cheap internet. We need to find a way to support dist-upgrades (perferable via the dist-ugprader mechanism) via cdroms.
It should both support the case when the machine is not networked at all or when the network is avialable but slow and expensive.
Data preservation and migration