Google Maps added two more ways to perform zoom, in addition to the plus / minus keys and the slider:
* left double-click to zoom-in one level, right double-click to zoom out
* zoom using your mouse wheel
Another new feature is a smoother transition when you zoom. Google uses some animation to emulate Google Earth's continuous zoom. This requires a broadband connection, or else you won't notice the difference. The feature is also available only on Windows if you use Firefox or Internet Explorer.
I wonder how close is the moment when Google Earth moves online.
Google Maps + Photos = Panoramia
View geographic data on Google Maps
Change the world with Google Earth 4