Here's an excellent screencast by a prominent tech journalist John Udell on how he uses tag powered del.icio.us to research a topic he might do a story on. Read: If you want to get in front of important journalists, consider writing niche articles and bookmark them with tags in del.icio.us along with articles and resources from other relevant sources.

This factors in to good online public relations research as well as online marketing/promotion for clients as "tagging" becomes more popular.

Chris Pirillo offers a search tool entirely reliant on sources that organize their content with tags, called gada.be.

On a similar note, Information Today highlights how Yahoo's recent offering of podcast search and displaying blogs in news search results can be useful in mining expert information as an alternative to traditional means.