I built gusanos on Ubuntu twice and on OS X. On all three, networking doesn't work properly. It just says connecting... and does nothing. The host is able to register properly and the clients are able to see the host on the server list.
I found a deb and tried that and it works great. I narrowed it down to the zoidcom library. If I rebuild CVS on Ubuntu with zoidcom 0.6.5 it works fine. I can't find zoidcom 0.6.5 for os x, the earliest I can track down is 0.6.6, which also doesn't work.