Building a CDN using Bittorrent?

I've been mulling something over for a little while, based on something from work... I'm thinking of a CDN which uses Bittorrent to replicate the files thereby reducing the need for major bandwidth infrastructure? It's just an idea, a mental exercise to keep my brain idling.

So far here are my thoughts:
- A pickup directory which is monitored by some form of service
- Once a file is placed in the pickup directory a torrent file is created and replicated to all of the edge sites (custom private tracker?)
- The torrent then seeds as usual until all sites on the network have a full copy
- Clients can then get a local copy of their data.

I'll work on this as a thought exercise a bit more over the coming weeks. I'm sure this is full of holes as it stands and maybe I've got the CDN part completely arseways when I say no need for major bandwidth!

I'm aiming for a cross-platform sort of idea. Possibly something web-based? I dunno. Might be interesting, we'll see where it goes.

Shaner