Anchor text is an established method for search engines to determine how others describe an external resource. As for tags, the study Can Social Bookmarking Improve Web Search, presented at the First ACM International Conference on Web Search and Data Mining (Stanford) analyzed 40 million Delicious tags and found that anchor text was a better signal for web search relevance. Part of the problem was scale of adoption. A lot of people have to adopt this new tagging method for it to be worthwhile to use across the web. And if Delicious tags don’t have the scale, how long will it take for Common Tag to? When I asked Yahoo about it this, they acknowledge that it may not be something that’s adopted web-wide. Rather, it’s a format of interest to a particular group of developers who have needs beyond that which is available through means such as the meta keywords tag and rel=”tag”. - × × ×