If you want to spend time hacking on bittorrent I'd very much recommend+1
looking at making bittorrent suitable for synchronizing the red
hat/fedora mirrors as quickly as possible then more/better failover and
mirroring support in the update tools.
Many of the commercial mass updating tools use multicast at the leaf nodes to enable parallel installs (e.g. labs of 200+ machines fully installed in 15 mins). Combining this with the mDNS, zeroconf stuff (with signed packages) would be very nice :-)
Carwyn