Throughout the site abbreviated dates are used (Apr 21 at 9:12). This works great for dates within the current year but it seems that as the years roll by it'll become important to include the year in the date. I am not sure that having the time is of value for a post that is a year old. Maybe at a certain threshold replacing the time with the year is appropriate.
Dates more than a year old do include the year. See for example: http://stackoverflow.com/questions/4