The Associated Press announced Monday that any website that uses its content must get AP permission and share revenue with the wire service. Any site that did not comply with these arrangements would face a legal challenge. A variety of online sites use AP content, from search engines like Google and Yahoo! News, to news aggregators like the Drudge Report that link to articles, and smaller sites that reproduce the articles in full.
You can read about the aggregating issue in the New York Times article found here.