El Goog has let Google Earth 5.0 out into the wild. The beta has new features in the form of historical imagery and timeline mechanics, ocean floor/surface data (see this story from digg for some more on that) and a new simplified touring system.

Looks like some of the 3D city imagery has caught up to MS Virtual earth too! I've always preferred GE to MS VE, but the MS system has had far more realistic looking city 3D views in the past. Check out this placemark in Vancouver as an example (ensure you have 3D buildings and and give it time to load all the textures).