Hello,
the latest version of Panoptis DoS/DDoS detection tool is out (version 0.1.1). A few fixes should make it more effective and stable. On another note, if you want to run it on FreeBSD all you have to do is compile Panoptis *and* the CommonC++ library with g++ 3.x (tested with 3.0.4). Earlier versions of g++ will break it. The same applies to GNU/Linux and (probably, have not tested it yet) Solaris.
You can download it from:
http://prdownloads.sourceforge.net/panoptis/panoptis-0.1.1.tar.gz
Get it, test it, feed back 
Costas