Hi,
on my force.com public site, the input date format uses the US format, but the public site guest user shows the time zone as GMT and locale as English/Ireland

The page is very simple and on another org, which looks identical to me, it is fine:
<apex:page standardController="Contact"  >
<apex:form>
<apex:inputField id="Date" value="{!Contact.BirthDate}" />
</apex:form>
</apex:page>

any ideas?