Wordpress - Edit "thank you for creating with Wordpress" in version 3.3.1

Credit definitely goes to @kaiser, but here is a full working solution. You can add this code to your functions.php file (in your theme):

function wpse_edit_footer() {
    add_filter( 'admin_footer_text', 'wpse_edit_text', 11 );
}

function wpse_edit_text($content) {
    return "New Footer Text";
}

add_action( 'admin_init', 'wpse_edit_footer' );

Just hook into the filter. The only thing remaining will be the <hr />.

/**
 * Change/Disable the footer text line
 * @return void
 */
function wpse_remove_footer()
{
    add_filter( 'admin_footer_text',    '__return_false', 11 );
    add_filter( 'update_footer',        '__return_false', 11 );
}
add_action( 'admin_init', 'wpse_remove_footer' );

In case you want to change it:

add_action( 'admin_init', function()
{
    add_filter( 'admin_footer_text', function() {
        echo "This is a custom admin footer text";
    }, 11 );
    add_filter( 'update_footer', function() {
        echo "This is a custom footer update text";
    }, 11 );
} );