As of Version 1.3.0, multi-device-switcher plugin has supported is_multi_device()
function. I'll use the function in multi-device-switcher, this plugin won't be maintained any more!
c.f.
http://blog.thingslabo.com/archives/000400.html
function isSmartPhone()
{
if (is_multi_device('smart'))
return TRUE;
return FALSE;
}