I needed to get a google map to center and scale based on the added points.
I found a tutorial here: http://econym.googlepages.com/basic14.htm
This gave me exactly what I needed.
In short, given a GMap2 object called map and a map of locations (name -> object with lat and lng properties):
map.setCenter(new GLatLng(0,0),0);
var bounds = new GLatLngBounds();