Street View is currently available in six U.S. cities: Chicago, Portland, Philadelphia, Tucson, Phoenix and Pittsburgh. And, it's not just the cities themselves, but out in the suburbs as well. The "blue" indicates where Street View is available:
Street View provides a 360-degree view at a given point on the map. Here's a look at our school, if you were driving by on Rt. 22:
Google Maps Help says: "To navigate along a street, click one of the white arrows overlaid on the street to move in that direction. You can also use arrow keys. Street names display within the info window. You can navigate on to another street once you reach the center of an intersection."
I grew up in the city of Chicago here:
The neighborhood is still looking pretty good. I wonder how often these views will be updated. Take a virtual walk!