Based on info at http://hacks.mozilla.org/2009/06/geolocation/ and https://developer.mozilla.org/En/Using_geolocation - the latter link looks better.

Your location will appear here if everything works...

Latitude: yyy

Longitude: xxx

Status updates: blah

Test results at October 2009:

  • Firefox 3.5.3 on osaka/MacOS X Leopard - working once I'd realized this is async code (the first link above isn't as clear as the second) Answer was 0.0000866 out on latitude, and 0.001052 on longitude when compared against the postcode database. Typing the 2 coords into Google Maps, the browser coords are across the road, the postcode is a bit further away at the train station.