During the last days a lot of blog entries, forum posts and even articles in IT magazines were made about a potential phpBB mass hack in preparation. From what is reported it seems to me that FuntKlakow is only a spambot and that the whole situation is a little bit overhyped. In the end it seems enough to enable the visual confirmation in the registration form (captcha) to keep FuntKlakow out, although the captcha is so bad that it should not be hard to break it.
Despite the comment made above, he doesn't suggest dismissing the issue just yet. It's quite possible that the "deception" of FuntKlakow being a spam bot is just that, and it could turn into a massive tool for some developer out there to flip a switch and have a huge amount of server-level access across the world.
Stefan also briefly mentions a patch that he submitted to the phpBB team concerning an issue with the signature_bbcode_uid remote code execution exploit - which wasn't used. Instead, an internal patch was applied that still didn't quite cover the issue.