Damaya, For the 2009 model year, none of the Lambdas, including the Traverse, will be offered as a hybrid. I definitely think it's in the cards sometime in the future, especially with the new CAFE standard approaching. Still, if you're in the market for a full size 7 or 8 passenger family hauler, you'd be hard pressed to find one that offers as much functionality and space as the Traverse with better, or even equal, fuel economy.
The Traverse will use a new variant GM 3.6L direct injection V6, which will produce 286HP and, most likely, slightly improve upon the Lambdas' already class-leading 16/24 MPG EPA estimates. Although nobody can say for certain, I'm expecting a 1mpg bump on both of these numbers for a FWD fuel estimate of 17/25 mpg.