Postcode AJAX request

What is the following postcode AJAX request for?

Found in address.tpl Is the idea it returns false for countries that don't have it and the postcode field is hidden?

My install returns a 404 on this request, any ideas where to look first? Is postcode required by standard or is it configured?

This checks if the country requires a postcode or not.. if not required it removes the * and disables the validation. If it is required it adds the * and enables validation

This for some reson broke my form when signing up for a new account, removed it and i didn't have a problem, the only thing that changed on my site was inserting a cufon font in the header.

Thats the only change i made, and even i removed the cufon font it still broke so commented out the ajax postcode check posted above and it worked.

My main question is, by commenting it out, does that cause a big problem even though it will work?

Thanks

Chris