In October 2010, event registration website Eventbrite blogged about how different types of social sharing turned into paid event registrations. Their most interesting data is quoted here:
When someone shares an event with their friends through social media, this action results in real dollars. Our most recent data shows that over the past 12 weeks, one share on Facebook equals $2.52, a share on Twitter equals $0.43, a share on LinkedIn equals $0.90, and a share through our ”email friends” application equals $2.34.
More and more, I believe that Facebook is more powerful than Twitter. It’s better for interactions (compared to just broadcasting), it’s stickier, and it looks like it generates more action-driven results.
Update: Entrepreneur Magazine agrees: http://blog.entrepreneur.com/2010/10/thoughts-on-twitter-versus-facebook-for-business.php