Redmine

Currently on http://www.redmine.org/projects/redmine/news:
    Redmine 0.8.2 released (5 comments)
    Added by Jean-Philippe Lang about 1 month ago
    ...
    Redmine 0.8.1 released (4 comments)
    Added by Jean-Philippe Lang about 1 month ago

The actual dates are 2009-03-07 and 2009-02-15 (more like 4 and 7 weeks ago).

I've seen dates formatted as ages on other systems that do not change units until the age is ≥ 2 x the-unit.
This provides better/more accurate information.

The algorithm goes along the lines of:

    if age < 2 hours then use minutes
    else if age < 2 days then use hours
    else if age < 2 weeks then use days
    else if age < 2 months then use weeks
    else if age < 2 years then use months
    ...