Make client doing annoying work of calculating their time, but make server do important task of knowing when to send timestamp.

gistfile1.rb

RUBY:
    # push timecheck command to clients every 30 minutes for rooms where client count is greater than 0
    timecheck = EM.add_periodic_timer(60*30) {
        @channels.keys.each do | key |
            if @channels[key][:clients].length > 0
                data = { :type => "roomnotice", :special => "timecheck", :msg => "heyo!" }.to_json
                @channels[key][:channel].push data
            end
        end
    }

JAVASCRIPT:

var months=new Array();
months[0]="Jan";
months[1]="Feb";
months[2]="Mar";
months[3]="Apr";
months[4]="May";
months[5]="Jun";
months[6]="Jul";
months[7]="Aug";
months[8]="Sep";
months[9]="Oct";
months[10]="Nov";
months[11]="Dec";
timestamp = function() {
	var date = new Date();

	var hours = date.getHours()%12;
	var minutes = "";
	var ampm = "";
	var month = months[date.getMonth()];
	var day = date.getDate();
	var year = date.getUTCFullYear();

	// am or pm
	if( date.getHours() < 12 ) {
		ampm = "am";
	} else {
		ampm = "pm";
	}

	if( hours == "0" ) { hours = "12"; }

	// set minutes
	if( date.getMinutes() < 10 ) {
		 minutes = "0"+date.getMinutes();
	} else {
		minutes = date.getMinutes();
	}

	var time = month + " " + day + ", " + year + ", " + hours+":"+minutes+ampm;

	// var msg = trash.createMessage( "roomnotice", time );
	// msg["special"] = "timecheck";
	//trash.trashio.sendMessage( msg );

	// $("#chat").append("<p class='chatitem roomnotice time'>"+time+"</p>");
	// $("#chat").animate({
	// 	scrollTop: $("#chat")[0].scrollHeight
	// });
	return time;
}

// when you receive the timecheck command:

$("#chat").append("<p class='chatitem roomnotice time'>"+timestamp()+"</p>");