Android Community has a great video on the actual workings of Google Maps Street View on the T-Mobile G1. Google Maps will certainly be a killer app on the T-Mobile G1 because of a feature that no cell phone currently offers--the ability to control Street View by just moving the device around, as if you were looking at the world through a looking glass.
Because the T-Mobile G1 includes an internal compass, it allows you to control your view of Street View by simply moving your body. You will be able to turn completely around with the G1 to "see" what's behind you on 5th Avenue, zoom in for amazing detail to see where the nearest parking garage is, and much, much more.
It certainly looks like Google Maps with Street View on the T-Mobile G1 will redefine mobile maps and challenge everyone who offers mapping programs to step their game up. Check out the demo in the video!