Check out the new additions to the Stats tab on plugins in the WordPress repository. A new pie graph shows a percentage breakdown of the versions being actively used by that plugin’s users. Only slices greater than 1.0% are shown and the results are currently not very accurate, as it’s only been up for one day.
The data will get better as reporting continues and these numbers will be useful all around – for both plugin users and plugin developers. If you’re a plugin developer, head over to the repository to check out your plugins and check out your usage data. As a plugin user, you’ll be able to see what percentage of other users are using what version of the plugin and weight that against the compatibility reports in the right hand column. When you’re trying to decide between several plugins that appear to do the same thing, any extra bit of information can be useful in the selection process.