I was hoping to use exactly something like this years ago, when I had to transfer tens of GB to and from Korea every day when I was working at Hammerhead Productions. Using rsync was painfully slow, because TCP/IP required acknowledgement of each packet -- and even though our bandwidth was high, our latency was very long, and we were getting less than 1 Mbps rather than the 10 Mbps we should have been getting.
Using something like BitTorrent, which uses UDP and does the error checking itself asynchronously would have been a huge help. We had multiple cable modems on both ends, and BitTorrent would have been perfect.
In the end, I wrote a simple tool which copied files using scp, but ran 10 threads with 10 separate scp calls and got almost 10 Mbps from each cable modem.
Aspera does similar things at insane prices.