The documentation states on() should be used in place of live for jquery 1.7.

For newly added elements, the 'click' event is working as of 1.7.2 (was broken in previous versions), but 'keypress' does not work with on() (works with live()).

$("input").live( 'keypress', function(event) {
	if ( event.which == 13 ) {
		event.preventDefault();
		alert("works");
	}
});
$("input").on( 'keypress', function(event) {
	if ( event.which == 13 ) {
		event.preventDefault();
		alert("doesn't work");
	}
});