After fifty years (OK, fifty two now), Sam and Marion Crane's hankipankerous hotel of choice still stands (at least, according to the google maps images of March, 2009 - there's a lot of redevelopment going on around there).
At the southeast intersection of South Central Avenue and East Jefferson Street. Central Avenue runs north - south through the city centre. Jefferson runs east - west, and is a bit south of the centre. In fact it's south of the city-crossing Van Buren - the other street of fame and of 50s motels.
This building now houses the Phoenix Police Museum. The window/door shown is the one just occluded by the front of the yellow bus shown in the other image. The museum's website appears reticent regarding the building's connection to the location shooting for Psycho. But I suppose, as nothing bad happened there, they wouldn't be interested.