WordPress.org

Finds the number each of your posts have been shared on Facebook and saves it as a hidden meta field.

The numbers are updated each hour through a cron job.

The update is non-blocking so visitors won't notice any performance degradation.

A widget for displaying most shared posts is included, and the output is easy to override.

I have only tested this on one site, but it works flawlessly for me. Please let me know if you have any issues. Fastest way to get a response is by Twitter: http://twitter.com/bjornjohansen