Neo Geo: Web Page To Test HTML5 Geolocation API

I'm looking into creating a location-aware Web-based game for an upcoming conference, and I need to know what level of resolution iPhone (etc.) geolocation supports. Walk around with an iPhone reloading Neo Geo for a while, and you'll have a ballpark answer; walk around with Neo Geo and a spreadsheet, filling in the details, and you can have an exact answer.

To be clear, I hosted this with WiFi and OS X "Web Sharing," which is actually an Apache server which looks for content in /Library/WebServer/Documents. So drop Neo Geo in there, turn on Web Sharing, and Bob's your uncle. Or, put it on your Slicehost (etc.) and you can ping it from all over town. (I was hoping to see long/lat vary just when I walked around my living room, but this did not transpire.)

Update: now hosted at http://neo-geo.gilesb.com/. Check it with your iPhone to find out your latitude and longitude.