Tessellation is an incredibly awesome tool, and to me is the most exciting thing to happen in games since dedicated physics cards. I am not joking. Having a card dedicated to physics computations alone is a fantastic concept, however it was severely limited by 1.) media/ news downplay, 2.) lack of support in games at launch, and 3). cost. The damn things are still $400.
Anyway, I hope that Tessellation techniques become as mainstream as shaders are now. That the makers of Dirt 2 have plunged right in is exciting -- their next games will be even more impressive as they refine their skills.
What else was really exciting about DX11? Free anti-aliasing?