I took two simple examples from Google Maps v.3 Documentation
https://code.google.com/apis/maps/documentation/javascript/examples/maptype-base.html
google-maps-utility-library-v3.googlecode.com/svn/tags/markermanager/1.0/examples/weather_map.html
And I tried to merge it, and its working http://nazin.gexe.pl/maptype-base.html
Where is the problem then? If you look at tile (4, 2) there should be some weather signs which is ok, but when you scroll map to tile (12, 2), (20, 2), (-4, 2) and so on, same markers appears here. Is there any way to show markers only in "default" tile which is (4, 2) tile?
Best solution I found so far is to create projection (Euclidean Projection) for CoordMapType and set scaleLat and scaleLng values big enough, so markers will repeat after "long distance".