Registration has been turned back on and the new reCAPTCHA plugin is active. It's definitely a lot harder for a computer to guess the text (even for a human it seems!)
Anyways, if that article is correct and all of the spam we've been getting was in fact from bots then this change should eliminate all spam.
You can see what it looks like if you logout and try registering. There is a fancy new captcha widget. It even has a sound captcha if you're having a hard time with the visual one. The sound will read out numbers that you have to type in and there is background noise in the audio. Fancy stuff! 8)