Have to say the A340-500 is my personal favourite; the -600 is a fine looking airplane no doubt, but I just feel the -500 is better proportioned.
Anyway, there's an interesting article on the Flight website today, about the next round of BA's widebody choice, expected in early 2009.
The airline is basically going to be looking at the A350-1000 (and -900) from the Airbus stable and, from the Boeing stable, "evolutions of the 777-300ER to a more radical design, and the 787-10". It excluded the 350 from the recently completed selection as it didn't believe it was sufficiently well defined and is also waiting to see how Boeing will respond.
http://www.flightglobal.com/articles...s-to-come.html
So, that pretty much confirms that there will be no 747-8 for BA and it would appear that the 777-300ER's chances are pretty slim unless it can evolve the current design (wonder what BA has in mind here?)