It is an amazing sample. I guess it also proves Google should stop changing the SOAP API, to AJAX API (not that the easy way of AJAX API currently hurts) but should NOW provide output=json,xml in the URL (a REST way).
REST rocks for one more time, and even Google GWT developers know it (and even propose it) instead of their apis.
PS. and yeah… there is a way, but it is supposed to be secret