jquery submit function not doing anything

Hey all,

This for some reason does not trigger alert:

Code:

---

<script>
 $('form').submit(function(){
alert('hello');
return false;
});
</script>
<form>
        <input type="text" />
        <input type="submit" />
</form>

---

Note that I know the jquery library is installed because otherwise firebug would raise undefined function for '$'.

Thanks for response