(1) Why not use Phil's proposal:
Bad Behavior/Bad Behaviour?

Looks very good! I'll test it. After the first quick look at it I wonder whether the script contacts a server where the filter rules are stored centrally (like Akismet does) or does the filter come with the script (and thus has to be updated from time to time)? (So far I only found a "whitelist".)

(2) We still need spam protection for the current versions!

Yes, absolutely! When I find a good spam protection I will also intgrate it in the current version (and also for the contact form).

Alex