Having difficulty displaying and centering map with user's location using W3C GeoLocation API

I'm using the following script and having difficulty passing in the lat and lon variables I created with user's location. When I remove the lat and lon variables I created and manually put in 0,0 it works fine for debugging's sake...The map should be displayed in a div with id of map_canvas.

$(document).ready(function() {
navigator.geolocation.getCurrentPosition(handle_geolocation_query,handle_errors);  
var lat = position.coords.latitude;
var lon = position.coords.longitude;
var latlng = new google.maps.LatLng(lat, lon);
    var myOptions = {
    zoom: 1,
    center: latlng,
    disableDefaultUI: true,
    mapTypeId: google.maps.MapTypeId.TERRAIN
};
var map = new google.maps.Map(document.getElementById("map_canvas"),
    myOptions); map.setTilt(45); 
});  

Your problem is probably right here:

navigator.geolocation.getCurrentPosition(handle_geolocation_query, handle_errors);

Presumably, handle_geolocation_query looks something like this:

var position;
function handle_geolocation_query(pos) {
    position = pos;
}

But navigator.geolocation.getCurrentPosition is an asynchronous function call:

The getCurrentPosition() method takes one, two or three arguments. When called, it must immediately return and then asynchronously attempt to obtain the current location of the device. If the attempt is successful, the successCallback must be invoked [...]

Emphasis mine.

So, your handle_geolocation_query callback will be called by getCurrentPosition when it has the position, not when you call getCurrentPosition. So, when you get to here:

var lat = position.coords.latitude;
var lon = position.coords.longitude;

Your position won't necessarily contain anything useful and you probably get an error telling you that position.coords is undefined or not an object or something similar.

You need to move your new google.maps.LatLng and new google.maps.Map stuff to inside the handle_geolocation_query callback where you'll have a useful position value.