JS function that takes an ISO time and returns a string representing how long ago the date represents.

pretty-date.js

/*
 * JavaScript Pretty Date
 * Copyright (c) 2011 John Resig (ejohn.org)
 * Licensed under the MIT and GPL licenses.
 */
// Takes an ISO time and returns a string representing how
// long ago the date represents.
function prettyDate (time) {
	var date = time instanceof Date ? time : new Date((time || "").replace(/-/g,"/").replace(/[TZ]/g," ")),
		diff = (((new Date()).getTime() - date.getTime()) / 1000),
		day_diff = Math.floor(diff / 86400);

	if (diff < 60) {
		return "just now"
	}
	else if (diff < 120) {
		return "1 minute ago";
	}
	else if (diff < 3600) {
		return Math.floor( diff / 60 ) + " minutes ago";
	} else if (diff < 7200) {
		return "1 hour ago";
	} else if (diff < 86400) {
		return Math.floor( diff / 3600 ) + " hours ago";
	} else if (day_diff == 1) {
		return "Yesterday";
	} else if (day_diff < 7) {
		return day_diff + " days ago";
	} else if (day_diff < 31) {
		return Math.ceil( day_diff / 7 ) + " weeks ago";
	} else {
		var months = [ "January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December" ];
		return months[date.getMonth()] + " " + date.getDate() + ", " + date.getFullYear();
	}
}