Armadillo,
Assuming the catcher had actually released a throw which either hit the BR or the BR prevented the pitcher from catching, sound like a good interference call.
As far as who is called out, I've already said I believe the proper call is that the BR is called out, the ball is dead, and the R3 is returned to 3B.
Here are the (OBR) rules that I believe support this contention:
	Quote:
	
	
		
			
				2.00 
BATTER RUNNER  is a term that identifies the offensive player who has just finished his time at bat until he is put out or until the play on which he became a runner ends.  
 
6.04 
A batter has legally completed his time at bat when he is put out or becomes a runner.  
 
7.08 
Any runner is out when_ ...(b) He intentionally interferes with a thrown ball; or hinders a fielder attempting to make a play on a batted ball; ..." 
 
7.09 
It is interference by a batter or a runner when: ...(l) He fails to avoid a fielder who is attempting to field a batted ball, or intentionally interferes with a thrown ball, ...
			
		 | 
	
	
 There is also the J/R cite posted earlier by Tim which also supports this ruling.
JM