It's simply a matter of drag and drop, but I wanted to replace this photo with another that had less sharpening, but I couldn't figure out how to do this.
I could imagine that this would be useful for those photogs visiting the city who want to get an idea of what time of day the lighting is best for some of NYC's landmarks. In my Flickr post, I mention that this was taken at 6:30 AM, and by coincidence, the satellite photo seems to have been taken at about the same time.
You also have the option of viewing just the street map or a combination of street map and satellite photo. You can do the usual right-click drag to move the map around, or if you nudge the scroll wheel of your mouse up, you can zoom in (beware of the scary groundrush effect).