Placeholder crossbrowser (para Explorer)

Paso de explicar.

getInternetExplorerVersion = function getInternetExplorerVersion(){
	var rv = -1;
	if (navigator.appName == 'Microsoft Internet Explorer'){
		var ua = navigator.userAgent;
		var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
		if(re.exec(ua) != null)
			rv = parseFloat( RegExp.$1 );
	}
	return rv;
}

if(getInternetExplorerVersion()!=-1){
	$('[placeholder]').focus(function() {
		var input = $(this);
		if(input.val() == input.attr('placeholder')){
			input.val('');
			input.removeClass('placeholder');
		}
	}).blur(function() {
		var input = $(this);
		if (input.val() == '' || input.val() == input.attr('placeholder')) {
			input.addClass('placeholder');
			input.val(input.attr('placeholder'));
		}
	}).blur();
}