lammert - 3:25 am on Sep 14, 2010 (gmt 0)

Opera is badly supported by Google's geo products. Google MapMaker doesn't work at all in Opera, not in the 10.62 release and not in the previous ones. MapMaker has about the same issues as you describe now with Google Maps. Ajax popups won't come. Maybe they shared some code between the MapMaker and Maps products to make the two systems more "compatible" with each other.