Ramifications of Rel Nofollow
I have been thinking more about this whole rel=nofollow function the search engines want people to use to indicate unreliable links, or links that can not be verified as being on topic by the webmaster. Something that has come up in the use of the nofollow attribute is the way it is being used. Some webmasters have started to use it for entire pages, telling the robots not to follow any links from that page. While this certainly will stop comment spam, or at least stop the perpetrators from gaining from it, it poses an interesting issue. What will happen to the whole link system if everyone starts using it in the above manner?
One of the reasons you don't want robots to credit outbound links is because they can indirectly take up your PR. Again, not that 'Page Rank' is used in any valuable way anymore, but we know that the engines do count links in order to determine a site's popularity. So if the robots don't see any outbound links, it will help the site keep what PR it has, but then no new sites can establish themselves because everyone will be hiding any links to them using the nofollow attribute. The effect this will have on the web is that established sites that are already important will remain so, while new sites will have a very difficult time getting themselves into SERPs on Google or Yahoo.
I am sure the big search engines have thought this through and they must be slowly de-emphasizing the value of inbound links in favor of some new method of determining a page's worth. Perhaps now they are looking at the real quality of the pages that link to a site. Truly there are only a handful of high ranking sites of value on the web, and to get a link from them, whether it is a nofollow or not should be considered to be a good link, links from other sources on Google's PR list should be considered lower. So I hope that the robots are still noticing the links and just comparing them to their importance table, even if they are not following them for crawling to continue to assign the importance scale. If the major search engines are getting away from using links as an indicator of value, its about time. People are gaming that in a way that no one can check for, they are buying links which Google and Yahoo can't control, so they will have to change to an internal site ranking policy that isn't based on links. So the nofollow attribute is probably a stop-gap measure until the new system is in place.
Search is these guys business, and they can't afford to have their searches not relevant. They couldn't sit around and watch people buy links forever. I just wonder what the new system will be based on. Perhaps it will be something deeper like how many other sites discuss another site, or the criteria that a site have actual natural language on it, and not just keywords. But probably what has happened is that enough people are using the Yahoo and Google toolbars that they can now determine statistically which sites are getting the most traffic and they can also see how many pages are accessed, and how long users stay on that site. Then they can perform analysis to determine how important the site is. That is why it was so critical for Yahoo to come out with a firefox version of their toolbar, it is imperative that they get as many data points as possible to establish their new algorithm.