By using 20 levels of color tones, Newzie can represent 20 time intervals starting from time interval corresponding to "with-in last 5 minutes" and growing exponentially till "more than 1 year ago" as shown in the color scale below.
Above, the first color tone represents the time interval "within last 5 minutes." For example if one post is published 40 minutes ago, the forth color tone is used for to represent its post-date which means that publication occured within last hour. If passed time is more than 1 year, the blue color, which is the last color tone in the scale, is used.
It has to be noted that while you are using Newzie, time passes. As time passes, the colors correspond to the publication dates change. In other words, newly updated subscriptions in the listview, which were represented with color 'red' is getting orangish first, then yellowish, and then greenish, if they haven't been updated during that time.
Time-based color coding is heavily used in the ListView of the Subscriptions Panel and for each post to give you the sense of when they were posted.