I think the matt one is a dummy. To my eyes, the whole top surface is plastic rather than glass, and that's why its less reflective. I'd imagine that it's just to demonstrate size/feel. Either way, I don't think that they'd even make demo units without the glass top, because its integral to the screen (i think anyway).
Also, this is a kick ass demonstration of the size of the tab compared to the iPad. Demonstrates really well why I lurve the Tab.
Galaxy S Running Darky's Raw Steel Edition v3.0 w/ Voodoo - The Fastest In Town