How to load jquery from plugin after wp 3.0 update?

Sence i’ve updated wp to version 3.0 it seems that all my ajax won’t work because jquery do not load.

I use this in my plugins

add_action('init', 'hauwidhud_init_method');
function hauwidhud_init_method() {
	wp_enqueue_script("jquery");
}

and I get “jQuery is not defined”.

So how do I properly initialize jquery in wp 3.0?

Regards,
Dan