Since I got fed up with all the spam I started getting on my forum page I started looking around for a spam thingy without success so I sat down and added one instead.
It is a bit of hack since I don't know much about neither trac nor python but it seems to work :)
The plugin adds an extension point for new posts and new topics and then adds an adapter to the "regular" spam filtering so you need to have the trac anti spam thingy installed and setup and working. I think maybe the adapters might have to be moved to their own module to work regardless of if the anti-spam is installed (since AFAIK tracdiscussion imports *) but I have not tested this.
Also I have only made this patch for 0.10 since I don't have any other version.
// MickeM