var uAgent = navigator.userAgent.toLowerCase();
var mobilePhones = new Array('ipad','iphone','ipod','android','blackberry','windows ce',
        'nokia','webos','opera mini','sonyericsson','opera mobi','iemobile');
for(var i=0;i<mobilePhones.length;i++)
    if(uAgent.indexOf(mobilePhones[i]) != -1)
        document.location = "http://"+ location.host +"/m" + location.pathname;