google_geocoder.php

<?php

// Google Maps API key
$key = key; // Google API key
$mapaddress = urlencode($listing['street_number'] . " " . $listing['street_direction'] . " " . $listing['street'] . " " . $listing['street_suffix'] . " " . $listing['street_suffix2'] . ", " . $listing['city'] . ", " . $listing['state'] . " " . $listing['zip']);

function geocoder($mapaddress){
  global $key;
  // Desired address
  $url = "http://maps.google.com/maps/geo?q=$mapaddress&output=xml&key=$key";
  // Retrieve the URL contents
  $page = file_get_contents($url);
  // Parse the returned XML file
  $xml = new SimpleXMLElement($page);

      // Parse the coordinate string
    list($longitude, $latitude, $altitude) = explode(",", $xml->Response->Placemark->Point->coordinates);
	$g_address = addslashes($xml->Response->Placemark->address);
	$status = $xml->Response->Status->code;
	$google_coordinates = $xml->Response->Placemark->Point->coordinates;      

	if ($status == 200) {
	// got legit code back, so save the lat/lon
	} elseif ($status == 602) {
	// invalid address so post error message and let them manually add marker 	
	}
}	

?>