Craft Time Diff brings in the Twig Date Extension.
- Place the timediff folder inside your craft/plugins/ folder.
- Go to settings/plugins and install timediff
The plugin adds the Twig time_diff filter (http://twig.sensiolabs.org/doc/extensions/date.html).
Renders the difference between a date and now.
{{ post.published_at|time_diff }}
- SensioLabs for writing the Date Extension