Tagging is interesting and fun, and people have been talking about it for a while. There is, of course, the term folksonomy that was created to compare to taxonomy.
One of the advantages of tags is that they should help inform a search. If I search for XYZ, I should be able to find documents that contain that phrase, that contain links with that phrase in the title, AND that are tagged with that phrase.
I know that Technorati tag search does this explicitly across blogs, photos, video, and music with tags applied directly to the content. And I would expect search engines to be able to find these. But what about tags that have been linked to a page, such as through del.icio.us or Ma.gnolia, where that term doesn't appear on the page.
So here is the question. Specifically, will the search highlight pages that have been tagged with a term that doesn't otherwise appear on the page? (Google does return results on del.icio.us with unusual tag terms. But I don't know if it improves the connection to the original pages.)