Google just recently announced its “freshness” update. Essentially this is an enhancement on it Google Caffeine that was rolled out last year. Google now can find content updates within in minutes and has the ability to display them on related search queries. Its latest algorithm update now puts a higher emphasis putting more recent content higher up on the results.
This change has affected 35% of the searches, so this may affect your rankings. I have noticed on a number of searches that contain reviews or news items, the date seems to trump other factors such as content relevance and page rank at least for a while. Once the post gets a couple weeks old, it seems to fall pretty quickly if it does not have any page rank.
With this latest change, fresh content becomes even more important. Blog posts, news releases, social media updates such as Facebook posts and shares, tweets, dated posts on your website need to be prioritized. Make sure your website updates are date stamped; update your xml site map frequently to help signal Google that a recent change has been made. New articles on your site or news items should have a posted date. Google recommends you use the following dating format: YYYY-MM-DD