Add to Any is a service that helps publishers spread their stories across the social web and helps readers share the stories they find particularly noteworthy. Naturally, the service keeps track of where people are doing the most sharing, and their answer is Facebook.
Mashable has more on the story, and Silicon Valley Insider points out that Twitter is already about half as popular as Facebook for sharing with only about one-tenth as many users.
Interestingly, email is a pretty feeble option for social sharers.
Really interesting chart! It is good to know where most of the sharing is taking place, especially for businesses.
good