We ended up doing exactly the same, I wrote a tracker for the bittorrent deploy system that is aware of our network topology and able to transport these 500Mb binaries to our frontend pool in < 3mins (300+ servers)

The tracker is opensource: https://github.com/hyves-org/p2ptracker

We're working on open sourcing more moving parts of our deploypipeline.

I'd be interested to compare notes on your system ?