Another open source IDS vying for its place in the sun is Tamandua. Version 2.0 was released in June 2003. It may be a good tool (I haven't used either Shoki or Tamandua), but I'm reluctant to try Tamandua. Most of the presentations are in Portuguese, and the project seems to be the offshoot of a commercial company.
At some point I'd like to have the skills necessary to turn projects I like into FreeBSD ports. That way, I can install, manage, and run them easily on my favorite operating system.