Michael Renzmann wrote to the ModSecurity mailing list recently announcing project ScallyWhack. It's a set of rules specially designed to detect comment spam against Trac installations. This is interesting for several reasons. It's a project with potential to be very useful for many people running Trac, it appears to be well thought out and well designed, but it is also the first independent project to focus on writing rules to fit a purpose. First of many I hope!