[Pavel M.]

в http://modernizr.com/downloads/modernizr-latest.js
сложнее проверяют

tests['touch'] = function() {
	var bool;

	if(('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch) {
	  bool = true;
	} else {
	  injectElementWithStyles(['@media (',prefixes.join('touch-enabled),('),mod,')','{#modernizr{top:9px;position:absolute}}'].join(''), function( node ) {
		bool = node.offsetTop === 9;
	  });
	}

	return bool;
};