In late 2008, the Hudson team released version 1.264 which added an anonymous reporting feature (you can opt-out in the "Manage Hudson" screen). The reporting feature has been sending information back to the Hudson team to help us understand how Hudson is used in aggregate; the info being reported includes the number of jobs configured, slave configurations, what plugins (and what versions of those plugins) are installed, and more. This data has not been available publicly until now! The raw data needed to be decrypted and scrubbed of any potentially identifying information, such as non-public plugin names or usernames in snapshot versions. We've finally scrubbed the data and are making it available!
The data is currently in monthly JSON bundles, organized by unique install key. We've filtered out reports of installations without any jobs configured, as well as any installations with only one report in a given month.