How Google Maps works
How Google Maps works: a look behind the Javascript of Google Maps. Whereas GMail uses XMLHttp to make calls back to the server, Google Maps uses a hidden IFrame. The method has its benefits. The push-pins and info-popups are a different matter. Simply placing them is no big trick; an absolutely-positioned transparent GIF does the trick nicely. The shadows, however, are a different matter. They are PNGs with 8-bit alpha channels. ...