Blog post about this feature: http://bilyukov.com/sitecore-publish-status-module/
Sitecore Marketplace URL: https://marketplace.sitecore.net/Modules/Publish_Status.aspx
The module adds a panel in the Publish ribbon of the Content Editor. When you select an item in the Sitecore content tree you can immediately see the current publish status for the English language and also there is a button to see the publish status for all languages.
There are 6 different statuses for an item:
- Latest is published
- Not latest revision
- Not latest version
- Not published for language
- Not published to database
- No publishing targets