Interesting so many people here are surprised at the precision of it, which shows HTML5 geolocation is doing well. (Though it comes down to how the browser gets geo data, I think some beyond Chrome are using Google, but not sure).

I notice its using the enableHighAccuracy flag, which probably helps. I've been told you also might be able to get better precision with watchPosition(), as the precision will get better with each call, though it's not used here.