Very cool.
Thanks for the link and thanks for taking a stab at a hard problem! Snow looks very promising so far... (I can ping nodes on my LAN over it too, which is usually a sticking point for traversal-oriented software - one is doubly-NAT'd, and there's an SSH server with an Ubuntu banner reachable from afar with UDP packets cutting through both brick walls nicely.) I'm impressed! :)
(FYI, building snow on a fresh Debian Squeeze 686-pae (packages: make g++ libssl-dev libminiupnpc-dev libnatpmp-dev) fails for me at dht.cpp line 220 (ambiguous function call) though; I'll have to read the source more to find the right cast or ::namespace to fix it but it compiles fine on amd64 with an identical set of packages.)
I'll definitely be reading the code more closely!