I am using the Google Maps API with parts in javascript and others in PHP.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
    <title>Google Maps AJAX + mySQL/PHP Example</title>
    <script src="http://maps.google.com/maps?file=api&v=2&key=ABQIAAAAA3fq9XBWvtS9ZYB0aG-cTRTkZyK8gYtfVqvwV6-79vPRam6nLBTe_uKtAZgMBEjBkeS1dJQ6LKQ1Cw" 
       type="text/javascript"></script>
    <script type="text/javascript">
    //<![CDATA[
    var iconBlue = new GIcon(); 
    iconBlue.image = 'icon.png';
    iconBlue.shadow = '';
    iconBlue.iconSize = new GSize(19, 19);
    iconBlue.shadowSize = new GSize(22, 20);
    iconBlue.iconAnchor = new GPoint(6, 20);
    iconBlue.infoWindowAnchor = new GPoint(5, 1);
    var iconRed = new GIcon(); 
    iconRed.image = 'icon.png';
    iconRed.shadow = '';
    iconRed.iconSize = new GSize(19, 19);
    iconRed.shadowSize = new GSize(22, 20);
    iconRed.iconAnchor = new GPoint(6, 20);
    iconRed.infoWindowAnchor = new GPoint(5, 1);
    var customIcons = [];
    customIcons["restaurant"] = iconBlue;
    customIcons["bar"] = iconRed;
    function load() {
      if (GBrowserIsCompatible()) {
        var map = new GMap2(document.getElementById("map"));
        map.setMapType(G_SATELLITE_MAP);
        map.addControl(new GSmallMapControl());
        map.addControl(new GMapTypeControl());
        map.setCenter(new GLatLng(47.614495, -122.341861), 13);
        // Change this depending on the name of your PHP file
        GDownloadUrl("phpsqlajax_genxml.php", function(data) {
          var xml = GXml.parse(data);
          var markers = xml.documentElement.getElementsByTagName("marker");
          for (var i = 0; i < markers.length; i++) {
            var name = markers[i].getAttribute("name");
            var address = markers[i].getAttribute("address");
            var type = markers[i].getAttribute("type");
            var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),
                                    parseFloat(markers[i].getAttribute("lng")));
            var marker = createMarker(point, name, address, type);
            map.addOverlay(marker);
          }
        });
      }
    }
    function createMarker(point, name, address, type) {
      var marker = new GMarker(point, customIcons[type]);
      var html = "<b>" + name + "</b> <br/>" + address;
      GEvent.addListener(marker, 'click', function() {
        marker.openInfoWindowHtml(html);
      });
      return marker;
    }
    //]]>
  </script>
  </head>
  <body onload="load()" onunload="GUnload()">
    <div id="map" style="width: 800px; height: 600px"></div>
  </body>
</html>
(I suppose the php will be called by
GDownloadUrl("phpsqlajax_genxml.php", function(data) {
...
in the javascript part of the sourcecode of phpsqlajax_map.htm)
Now I need another php file and the code snipplets for it, which creates an input form where I can add some new locations to the google map. Following code is used to create the xml file here: http://detektors.de/maptest/phpsqlajax_genxml.php The next step would be, trying to make an plugin for wordpress that I could easily post a blog entry with a new location on the same map, which displays already some other locations stored in the mysql database.
thanks!
<?php
require("phpsqlajax_dbinfo.php");
function parseToXML($htmlStr) 
{ 
$xmlStr=str_replace('<','<',$htmlStr); 
$xmlStr=str_replace('>','>',$xmlStr); 
$xmlStr=str_replace('"','"',$xmlStr); 
$xmlStr=str_replace("'",''',$xmlStr); 
$xmlStr=str_replace("&",'&',$xmlStr); 
return $xmlStr; 
} 
// Opens a connection to a MySQL server
$connection=mysql_connect ($host, $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
}
// Set the active MySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
}
// Select all the rows in the markers table
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
}
header("Content-type: text/xml");
// Start XML file, echo parent node
echo '<markers>';
// Iterate through the rows, printing XML nodes for each
while ($row = @mysql_fetch_assoc($result)){
  // ADD TO XML DOCUMENT NODE
  echo '<marker ';
  echo 'name="' . parseToXML($row['name']) . '" ';
  echo 'address="' . parseToXML($row['address']) . '" ';
  echo 'lat="' . $row['lat'] . '" ';
  echo 'lng="' . $row['lng'] . '" ';
  echo 'type="' . $row['type'] . '" ';
  echo '/>';
}
// End XML file
echo '</markers>';