var months = new Array("January", "February", "March", "April", "May", 
    "June", "July", "August", "September", "October", "November", "December");

var dateObj = new Date(document.lastModified);
var lmonth = months[dateObj.getMonth()];
var date = dateObj.getDate();
var fyear = dateObj.getFullYear();
document.write("Last updated " + date + " " + lmonth + " " + fyear + ".");