Google's had StreetView for awhile and Bing recently introduced Streetside imaging to their maps. Now, MapQuest is entering the ring with their street-level imaging, which they've dubbed "360 View."
360 View isn't available everywhere, so MapQuest is providing coverage maps, similar to what a wireless communications company might provide to show you where you can get a signal.
MapQuest also took great care in pointing out that you don't have to download a non-standard media player (cough, cough Silverlight).
