Those of you with blogs know what a pain it can be when the spammers send their bots out to muck up your comments with links to their own sites. They know the value of a link in Google and they frankly don't care whether they're messing with the rules or messing with you — they simply want links from anywhere to raise their search engine placement.
Maybe not anymore — Google has an idea! A new attribute that stops the Google spiders from following a link. You can place it dynamically every time someone leaves a link in your blog. Google says:
From now on, when Google sees the attribute (rel=”nofollow”) on hyperlinks, those links won't get any credit when we rank websites in our search results. This isn't a negative vote for the site where the comment was posted; it's just a way to make sure that spammers get no benefit from abusing public areas like blog comments, trackbacks, and referrer lists … We think any piece of software that allows others to add links to an author's site (including guestbooks, visitor stats, or referrer lists) can use this attribute. We're working primarily with blog software makers for now because blogs are such a common target.
Blog software makers are whole-heartedly jumping on the bandwagon to implement this strategy. If you've created your own blog, you may want to add this attribute in yourself. You can read all the details at The Google Blog.