One of the techniques I mentioned off-hand in Stopping spambots with hashes and honeypots was to mark all out-going links with rel=”nofollow” to negate the search engine incentive to spammers putting links in your comments. Turns out Wikipedia has just turned this on for all their outgoing links (I think: the announcement was pretty terse, and actually makes it sound like a temporary measure).

When a small-time blogger does this for their comments, it’s no big deal. But when Wikipedia does it, it is a huge deal. Wikipedia is an 8000-pound gorilla in the Pagerank ecosystem. A change to how they treat their external links will make waves. Naturally people are debating the issue.

Aside from all of the web-societal implications, the debate is exposing some new ideas: Google Blogoscoped mentions the idea of a “fading nofollow”: links start with a nofollow attribute, and then over time, lose it. The idea is that spam links will be found and removed, and will not get a chance to age to the point that they lose the attribute. Over time, most links will lose the nofollow, so the site as a whole will contribute to the search engines rankings, while spam links won’t survive past their probationary period. Clever.