According to the Application Helpers guides, you probably want
%p = time_ago_in_words(my_date) ago
For reasons I don’t quite understand, this documentation is also incorrect:
time_ago_in_words(2.days.ago) # => "2 days ago"
The actual behavior is:
time_ago_in_words(2.days.ago) # => "2 days"
I’m planning to move some of this into the padrino-framework project directly. Incorrect documentation is worse than no documentation; maybe it will be more accurate if kept in the code. :)