jEdit has a good feature where, when installing plugins, you can check a box to pull down the plugin source as well. This facilitates bug-fixing (for those interested) as well as code sharing. The option would be on the plugin install page. In jEdit this is a global option (I think), not per-install or update. The goal would be to encourage development, bug-fixing, etc. among the plugin users. For example, it would make it easier to find the source of an exception if the plugin had not been updated when the plugin API had changed.