Wake Turbulence of large aircraft is a non event because they do not climb as fast as a smaller aircraft.
Why, in that case is a 2 minute separation applied between a heavy and a smaller aircraft?. You may out climb the wake on 2 engines but you will be right in it if you lose one. Also consider that a lightly loaded heavy aircraft, particularly a large twin (777, A330) will rotate at about the same place as a 737/A320 type aircraft that is heavy. Wake turbulence can be pretty scary stuff, I've had some nasty encounters even when all the distances and timings where correct.
I suspect the A380 may need another minute added to the departure timing and a little more spacing on the approach. I guess it will be looked at during certification but it's going to punch a mighty big hole in the air.