I agree with azuko, the plugin does require major work. I was bit disturbed by the fact that one plugin could lockout/shut down every site using it. After the incident a lot of people have been looking into the code, and how it validates good bots like Google and Yahoo is appalling, and could potentially block out good bots and kill your SE rankings. Read IncrediBILL’s post: http://incredibill.blogspot.com/2007/12/bad-behavior-advisory.html
I highly recommend no one use it until it has some major improvements
