The Official Google Blog says they have A whole new world to explore. Google Earth 4.3 was released last night with a bunch of new features, including better 3D buildings, a sunrise mode, integrated street view, and various other goodies.
The 3D buildings are not all as good as Microsoft's Virtual Earth, which, while I'm no MS fan, I have to say their 3D cities are much more complete than Google Earth. GE 4.3 closes this gap somewhat. Of the two cities I quickly explored Seattle had only a few photo-realistic buildings, and lots of grey boxes, but San Francisco was f-n gorgeous. I'm sure there are other areas. See the link for downloads and more details.