Time-ago-in-words

It would be nice to have smart function that, depending on the local time and the message timestamps decides which is the correct format to display when necessary. For example, if the message timestamp is some time today, I would print it in "hour:minute" or a "Just now" format, if it was yesterday, we could use "yesterday at hour:minute", if it was before yesterday but less than one week, "day-of-the week time:hour", if was more than a week "Month, day", and so on...