Overlay -> Clone mode options, Theater mode 4:3 or 16:9 (catalyst 3.8)
 

Doesn't seem to make any difference at all no matter what setting I use (I
have a 16:9 TV). TV-out aspect stays 4:3 despite the 16:9 setting. Anyone
else have similar problems? (not that it's a big problem, I can always
change the aspect of the tv to get a proper size picture)