Forgive my ignorance... but why would anyone want their URL 'forgotten'. If they want to hide from the search engine, isn't that what robots.txt is for?
If CNN has an article about my drunk driving record 10 years ago, I can force Google to "forget" said CNN article, even though I don't control CNN.com's robot.txt.
No, they don't forget the article. They forget the link between your name and the article - searching for other words in that article will still bring it up.