For my collection of testcases of web technologies (check it online at ariya.github.com), I added a simple example demonstrating the use of HTML5 Geolocation feature. It should run without any problem on a web browser which has such support, including on several mobile devices which I have tested.
I also added reverse geocoding using Google Maps API which should give the approximate human-readable address of the location.
Point your browser to ariya.github.com and choose Geolocation link. Have fun!
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