I want to be able to distribute bundles of files, about 500 MB per bundle, to all machines on a corporate "extranet" (which is basically a few LANs connected using various private mechanisms, including leased lines and VPN).
The total number of hosts is roughly 100, and the goal is to get a copy of the bundle from one host onto all the other hosts reliably, quickly, and efficiently. One important issue is that some hosts are grouped together on single fast LANs in which case the network I/O should be done once from one group to the next and then within each group between all the peers. This is as opposed to a strict central server system where multiple hosts might each fetch the same bundle over a slow link, rather than once via the slow link and then between each other quickly.
A new bundle will be produced every few days, and occasionally old bundles will be deleted (but that problem can be solved separately).
The machines in question happen to run recent Linuxes, but bonus points will go to solutions which are at least somewhat cross-platform (in which case the bundle might differ per platform but maybe the same mechanism can be used).
That's pretty much it. I'm not opposed to writing some code to handle this, but it would be preferable if it were one of bash, Python, Ruby, Lua, C, or C++.
I think all these problems have been solved by modern research into p2p networking and well packaged into nice forms. A bit of script and bit torrent should solve these problems. torrent clients exist for all modern OSs, then a script on each machine to check a location for a new torrent file, start the DL, then delete the old bundle once the DL has finished.