Overusing JavaScript closures?
What you have there is actually just a fancy assignment operation. The closure there plays no role. And if you would need to set another placemark, you would have to repeat the code or wrap in one more function.

IMHO, it would be much more pragmatic to use a lot simpler approach:

var createPlacemark = function (point, placemark) {
        point.setLatitude(100);
        point.setLongitude(-100);
        placemark.setGeometry(point);
        return placemark;
    },
    myPlacemark = createPlacemark(ge.createPoint(''), ge.createPlacemark(''));


This way you get reusable routine with a clear name. And if goal of this all was to prevent external sources from adding placemarks, just warp it all in the standard:

(function () {

}());


The bottom line is: you were over-thinking it.