I just tested, and the captcha does appear to be broken in such a way that it is impossible to make new accounts.
I sent him a private message. This does not guarantee that he's seen it, but it's the best contact method I have handy.
Message received. Dave or Wes will have a look tomorrow. Other, more reliable method of contacting me: raise a bug report at http://code.google.com/p/lesswrong/issues/list
Things to check in general when this happens (I don't know if any of them are relevant in this particular case):
Is Javascript enabled? Including third-party sites?
Are cookies enabled? Including third-party cookies?
Are you blocking or spoofing the referer?
After turning on scripting, cookies, and referer, open the registration page again, by clicking a link or copypasting the URL rather than by refreshing the page.
A friend recently said
For some reason, LessWrong is not letting me register an account. It keeps telling me that I'm getting the CAPTCHAs wrong, even though I'm not.
Does anyone know the solution to that?