Google talks about a new search feature on their blog:
We've long believed that personalization makes search more relevant and fun. For nearly five years, we've been tailoring results with personalized search. Today we're announcing a new feature in search that makes it easier for you to mark and rediscover your favorite web content — stars.
With stars, you can simply click the star marker on any search result or map and the next time you perform a search, that item will appear in a special list right at the top of your results when relevant. That means if you star the official websites for your favorite football teams, you might see those results right at the top of your next search for [nfl].
Read the entire post on The Official Google Blog.