I run a very quiet server where people can sometimes be idling for hours, and my users have requested timestamps in chat

http://img.127001.org/img/2013-06-04_14.19.47.png

The timestamp in the screenshot was obtained with

new SimpleDateFormat("HH:mm").format(new Date());

I could send a PR, but I'm not sure whether you'd want to cache the SimpleDateFormat object rather than create it anew each time, or what token you'd want to use for the timestamp (%time breaks the single-letter-is-abbreviation-of-longer-word convention you have)