I have seen several techniques used to format dates in blogs and forums threads. This is the technique that worked for me.

1. Create a file called config/initializers/date_formats.rb with the following contents:

   ActiveSupport::CoreExtensions::Time::Conversions::DATE_FORMATS.merge!(
    :date => '%m/%d/%Y',
    :date_time12  => "%m/%d/%Y %I:%M%p",
    :date_time24  => "%m/%d/%Y %H:%M"
   )

2. Set the date variable:

   @cacheExpiresAt = 10.minutes.ago

3. Format the date:

   <%= @cacheExpiresAt.to_s(:date_time12) %>

The :date_time12 parameter to the to_s method simply chooses the formatting from the DATE_FORMATS hash. This technique lets you centralize all date formatting in your application.