Slight change:
$(document).ready(function() {});
Is equal to:
$(function() {});
As of jQuery 1.4: $().ready(function() { });
no longer works correctly in all cases. From the release notes:
As of jQuery 1.4, if you pass no arguments in to the jQuery() method, an empty jQuery set will be returned. In previous versions of jQuery, a set containing the document node would be returned.