When does Google Maps update Street View?
October 14, 2011 6:45PM
Street view photos are updated on a continuous basis, but there is a tradeoff between adding new cities and keeping the existing street view imagery current. More new cities are added every day in addition to existing imagery being updated, but it may be several years until a given city is updated.
See related links for more details including list of cities by country where Google's fleet of Street View cars are currently driving.