Weirdness in jQuery supplied with WordPress

There is a difference with the version of jQuery supplied with WordPress as outline on the Codex page for wp_enqueue_script:

Note: The jQuery library included with WordPress loads in “no conflict” mode. This is to prevent compatibility problems with other javascript libraries that WordPress can load.

Change your script to reference the jQuery object with jQuery rather than $, passing the jQuery object as $ so you can use it as you normally would within:

jQuery(document).ready(function($) {
    $('#something').html('something');
});