We could all learn a thing or two by paying attention to the marketing metrics and measurements that Facebook is sculpting… 

As we indicated earlier, today we are introducing new guidelines that will change how applications are ranked in the application directory. Currently, the focus is on total number of users, but going forward it will be based on user engagement. This is an important step in the evolution of Facebook Platform which will help drive the growth and distribution of applications that focus on user engagement and utility.

Facebook Developers | Facebook Developers News