I used to use one with my Mini, which had the same integrated graphics as the first gen MBA. It worked fine for everything except two WUXGA panels, which are blurry.
If you look on the Matrox website, 2xWUXGA can only go to 57Hz, which is a way of saying it does not work for most digital panels...
I will hook the matrox up to the MBA and see how it works.