It's a custom field for SharePoint 2010. When the solution is deployed there's an option to create a Livestamp column in your lists. When creating a new column you need to select a related date column. If the date column holds a date or datetime value, the Livestamp column will render the related, auto-updating, timeago text.
Solution package and source code are available at Codeplex.
- Added support for Calculated and Lookup columns with DateTime output
- Sorted column selection (alphabetically)
- Initial release