Look at the top rated answer at this url:
What is the best way to detect a mobile device in jQuery?
Current methods from that thread:
var isMobile = navigator.userAgent.match(/(iPhone|iPod|iPad|Android|BlackBerry)/);
Jquery:
$.browser.device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));