We've had spambots registring users on this site pretty much from day one of the relaunch. On average, we're blocking close to a hundred spam registrations per day. To put that in perspective: the number of users rejected in the past four months exceeds the total number of registered users.
The good news is the spam filter seems to be pretty darned good at blocking fake users. But I still want to look into better ways of stopping such things. In all likelihood, it's only going to get worse. Might as well get a head start on it.