I have implemented Mark Pilgrim's recipe to block spambots and various annoyances that hit this site on a regular basis. I will continue to add more counter-measures in the future, including banning offending IP addresses from accessing anything on my whole domain (I even think of banning an entire block from China, namely 202.108.*, from where all the requests are some variant of spam attacks). This will not be the sheer IP banning from comments, but access denied on any request.
It is a very big hammer to crush flies. And to borrow Mark's words, those that resemble flies from a distance shouldn't come too close. If you are banned from this site and think this is an error, you know how to contact me.