It works perfectly with the aquarium. As far as the program thinks - you just have a single display (in my case a 3840x1024 one).
It's not perfect for everything though. Opening a PDF on the above comp at work results in Acrobat launching over all three monitors resulting in an extremely letterboxed program window.
Running the fullscreen cowerflow mode of iTunes is gorgeous though - I'ts like flipping through your vinyls!