You seem to have forgotten to load the Maps API
http://code.google.com/apis/maps/documentation/javascript/tutorial.html#Loading_the_Maps_API
You'll probably want to move your javascript to be inside the <head>
section too
I repeat, you seem to have forgotten to load the Maps API, see
http://code.google.com/apis/maps/documentation/javascript/tutorial.html#Loading_the_Maps_API
You'll probably want to move your javascript to be inside the <head>
section too, to make the page HTML valid