An internet prankster tells Boing Boing:
Early this morning in San Francisco, Bush Street was changed to Obama Street along its entire length, from Presidio to Battery. If you link to this, please link to the "obamastreetsign" tag as there will probably be many other photos of the changed signs. (Or perhaps wait for an official statement from whoever is responsible.)
flickr link for evidence/images. Snapshot cropped above courtesy Tim Pratt.