The docs of Google Maps V3 JS API does not seem to give the interface of the construct of google.maps.Icon. I found an example with MarkerImage, wh
google.maps.Icon
MarkerImage
Hmm... Now, this answer is just wrong.
You can't
var icon = new google.maps.Icon({ anchor: new Point(...), url: "myurl" // etc.. });
It's an object literal, which means that you can just use it like this:
var icon = { anchor: new Point(...), url: "myurl" // etc.. };