html5, modernizr, yepnope, webforms2 issue

Question

I am trying to use polyfills for the first time for a HTML5 form and I only want to serve the code to the browsers that need it (thus modernizr2/yepnope).

First thing to add is that the javascript is definately loaded on FF3.6 for example, so thats not the issue.

Basically this is my modernizr/yepnope code:

<script>
    $(document).ready(function() {
        yepnope({
            test: Modernizr.input.required && Modernizr.input.placeholder && Modernizr.input.pattern && Modernizr.input.autofocus,
            nope: '/_scripts/polyfills/webforms2/webforms2-p.js'
        });
    });
</script>

In my HTML5 form i have various input fields with the placeholder attribute, and it all looks lovely in the newest browsers (FF4, etc) yet when I run it on FF3.6 I see nothing. Yet all the various other demos i see on the internet using webforms2 seem to have placeholder elements fine.

I have other html5 form things I want webforms2 to polyfill but the only one seemingly in action is 'autofocus' working on the top field.

Am I missing something really obvious somewhere?

Any help/suggestions much appreciated.

Adi.