Yahoo recently introduced the ‘robot-no content’ tag which allows users to specify what content they do not want the search engine spiders to crawl due to irrelevance. This ensures that the search engine crawler will only look at relevant information. This will help bridge the gap of having a website that caters to users or search engines. With this content filtering, it could be possible to have a website that does both.  This new concept will help webmasters in optimizing their sites better. Sometimes, there’s content on the site that isn’t quite relevant to the main content of the site; for instance, privacy statements, mission statements, terms and conditions, etc. Instead, you can get the Yahoo search engine crawler to only look at the content in which you would want them to by applying this ‘robot-no content’ tag to certain parts of the page that indicate to Yahoo’s search engine crawler what parts of the page are unrelated to the main content and are only useful to visitors.
This does sound a lot like cloaking, which is a practice in which webmaster will serve up a specific page to the search engine spiders and a different page to visitors. This is a practice that is frowned on by the search engines. However, this content filtering is not considered cloaking because all of the content is available.  Could this cause a negative effect in the world of SEO? When I hear about this new concept, it sounds great and will be very helpful for those that won’t abuse it. Unfortunately, like everything else, this too could be abused. By being able to block out certain content on a website, this leaves black hatters and spammers open to use this in a negative way in order to get higher ranked results. Because this concept is still very new, there isn’t too much news out on it at this time. My main question to Yahoo! would be what parameters have been set in order to ensure that no one abuses this service? We all know that if you are going to offer up such a service, somewhat strict parameters should be attributed to it.  So far, there isn’t any word out on Google, MSN or Ask moving in this same direction. As of now, Yahoo is the only one. Perhaps the other search engines are using Yahoo as the guinea pig, which could be a smart move. However, the implementation of this new tag will help the search engines, (Yahoo! only at this time) better determine relevance for a website which, in the end, will help them in serving up more relevant results to its users.

Sources:
http://www.searchnewz.com/blog/talk/sn-6-20070503YahooAllowsContentFilteringforSEO.html
http://www.ysearchblog.com/archives/000444.html
http://googlesystem.blogspot.com/2007/05/yahoo-lets-you-delimit-unimportant.html