I'm done fighting the OCR spam bots. The forums will be down until I get the new OCR resistant human authentication method up. It shouldn't take too long.

UPDATE:
The new captcha algorithm is in place, along with some other various forums bugfixes. I tested all possible action paths (new account registration, account activations, and password changes) and everything seems to be working well. Now all we can do is sit back and see if the spam bots figure out the new protections. The default captcha that comes with phpBB2 is pretty simplistic, so I'm not that surprised that OCR spam bots could read it. I doubt they'll have much luck with this one though. Only time will tell.