Q3 maps in the maps menu will load the levelshots \ mapname.tga and display it. Maps menu no longer automatically refreshes each time it is entered (DarkPlaces digs through each .bsp entities to find the map title and read the map format -- with tons of maps this is slow). Spacebar in the maps menu will refresh the list manually (in the event you added a new map). (The maps menu is "Help and Ordering").