http://gizmodo.com/5442625/project-natal-consumes-just-15-per-cent-of-the-xboxs-cpu-power
Given that devs will be strapped to 85% of the CPU power whenever the Natal unit's doing its thang, I doubt we will see many AAA titles with it truly integrated.
From what I've heard, the tech involved is truly impressive, but I think the cost is just a bit too steep, and I'm not talking about the price tag.