dm145's statement is a bit misleading.
"html5 geolocation" is an inaccurate term.
What he meant to say is that some web apps can now access your system's 'location' service, which in term can be as accurate as real GPS.
If your computer doesn't have real working GPS and/or Win8's live tile doesn't access that, there's nothing you can do other than just manually punching in your zipcode or town/city name.
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