The new feature is a more transparent way to personalize search results; this time, Google allows users to decide which search results are the most relevant and to share those findings with other users. Instead of bookmarking the results or saving them in Google Notebook, you can make them more visible on a search results page and find them when you search later. Unfortunately, Google’s interface will become cluttered unless Google decides to hide the new options until you click on a link like “Edit the search results”.
Of course, the big question is if / how a user’s feedback will affect result ranking for everyone else. Given Google’s experience with fighting spam, I’d imagine they’d know better than to provide an easily gamed feedback.