The spambot has been spreading because of Opera Community's decision to disable "captchas" - images of distorted words that are meant to be easily read by humans, but almost impossible for machines to read. Captchas do present an extreme challenge to those who cannot view images - such as those using text-mode browsers, or those who are blind.
They have been replaced with a different type of Turing test - a yes/no question. So, a spambot has a 50/50 shot of getting it right. Not only that, but WillYum found out that the Turing test doesn't even work! So, it's impossible to get wrong!
I personally feel that the captchas should be re-enabled - the accessibility issues can be worked around - for example, by providing a contact e-mail address for new accounts in which the user cannot read the captcha.
Several prominent members here have either had to disable comments, or disable anonymous comments, because of this. I personally have left ALL commenting enabled. Keep in mind, however, that spam will still be deleted.
If you see spam on ANY blog's comments (or, for that matter, a spam blog), report it in this forum thread.