Hands up who remembers the <blink> tag? Hands up who remembers Microsoft adding proprietary tags to HTML? Each time someone extended (and broke) the HTML standard the internet community got their pitchforks and flaming torches and stormed the castle proclaiming "Standards are good, proprietary is bad". Now google has done the same thing and Scoble, Winer et al are proclaiming them as saviours.
So why the imbalance? Why is google allowed to break a standard without any questions being asked? Why is google suddenly a darling when Netscape and Microsoft were decried for the same action? Sure it's nice to have an attribute to stop referral and comment spam but lets face it spammers won't care, they'll still spam and your comments pages will be full of their ads for viagra, rolex watches et al. You'll still have to clean and cull, it's just the links will no longer affect a site's page rank or get them crawled quicker.
Scoble describes this as a customer win (I'm sure Netscape said the same thing about <blink> and Microsoft said it about <marquee>); I don't believe it is.
It's just another proprietary HTML extension added by another corporation. Unless and until google submit their new attribute
to the w3c and make it part of the HTML standard I think I'd rather have my HTML
[update 14:10] Just to clarify the "proprietary HTML extension" comment. It's not an extension as such, the rel attribute is part of the HTML spec. However "nofollow" is not in the list of valid link types. The specification states that
"Authors may wish to define additional link types not described in this specification. If they do so, they should use a profile to cite the conventions used to define the link types."
Currently no profile exists. So perhaps I was a little harsh <g>