WordPress.com won’t implement Captcha. As a reply to my suggestion, that I would like to see this as an option for every user, they wrote:

Captcha will not be used here. Aksimet is much much more effective than any captcha system.

Uhm, yeah, whatever. Meanwhile, even this tiny insignificant blog received 37 comment spams overnight.

It’s always interesting how open source people sell their integrity just as much as their closed-source counterpart once they smell money. Of course WordPress.com has to push Akismet. It’s their product. You can’t make money with Captcha.