Mike
The imagery in WW is still better, but Google Earth has unbelievable potential. Check out Cambridge,MA if you haven't already. 6 inch resolution!The 3d buildings is a cool touch but will be better when Google is done with it. Supposedly they are rigging up trucks with lasers and cameras on them to drive the streets mapping buildings. So you will be able to get a true to life scale and full color 3d perspective in cities. Also check out googlearthhacks.com. Live weather radar overlays is probably the coolest thing. The flickr plugin is pretty cool too. It pulls the latest pictures of the area you are viewing from Flickr's photosharing site. Most of the stuff there is just placemarks to interesting sites but some of it is pretty cool.
On the WW side you can get all of the GE's imagery in WW, but until they fix their CPU usage issue it just can't compete. One downside to GE is that you can't run it offline because of the authentication thing it does when it starts up.
I'm hooked on this stuff.