I\'m building a map using the google v3 api because it is way faster. Essentially, it\'s a map of an area with about 30 cities with polygons over the regions. When a user hovers
Maps API V3 events are defined per object. Doing a search on the V3 reference page reveals that Marker is the only object with definitions for mouseover and mouseout. So yes, you appear to be correct.
By the way, there are people doing this, but it looks pretty involved:
http://groups.google.com/group/Google-Maps-API/browse_thread/thread/4ddc4f5888994563