Previously, businesses had to acquire 10,000 fans (or likers, or whatever you want to call them now) in order to gain access to analytics data such as the number of impressions each post generates, as well as what percentage of fans either "liked" or otherwise interacted with a post. It also involves monthly active users (MAUs). Page administrators for small businesses will be able to view such information retroactively to June 25, 2010.
http://www.clickz.com/clickz/news/1928582/smbs-applaud-newly-facebook-page-analytics