The vitality score for a project is calculated like this: (announcements * age) / (last_announcement), ie. the number of announcements is multiplied by the number of days an applicaton exists which is then divided by the days passed since the last release. This way, apps with lots of announcements that have been around for a long time and have recently come out with a new release earn a high vitality score, old apps that have only been announced once get a low vitality score. The vitality score is available through the project page and can be used as a sort key for the search results (definable in the user preferences). The original implementation of the vitality score is courtesy of Walles <d92 dash jwa at nada dot kth dot se>.