If you do any searching on Yahoo! regularly as I do daily, you may have noticed that there has been a slight change to the search results.
Of course, if you are looking at the page you won't likely see it, unless you can read the HTML as it is executing, but if you were to look at the HTML you would see that there is a new link on the page - one that is for all intents and purposes invisible, but one that could change the search landscape quite substantially.
We've seen these "new" links on other engines, most notably the new and improved MSN, but not anywhere else. I'm talking about RSS feeds for search results.