With multiple 1920x1080 screens, every bit of space is useful.  I currently have 2 screens running at 1920x1080 and 1280 x 1024.  The additional depth helps with certain software and eventually I'll be replacing the 19" LCD with my 24" TV as the second screen.
It's a complete waste of screen area and only needs to be on the primary display.
	
		
			
		
		
	
				
			It's a complete waste of screen area and only needs to be on the primary display.