Nofollow:

Let no fellow nofollow, lest we all lie fallow. A cogent article on the rel=nofollow initiative from Ben Hammersley’s Dangerous Precedent. I diverge from him, however, in that my understanding that the goals of this initiative are not to prevent comment spam directly, but to contribute, in a small way, to reducing the potential value comment spam. I agree that the assumption that comment spammers do it because of page rank is dubious and the evidence to support the assumption is lacking.