According to a salesmen at a Nokia booth after being asked the question: How about battery life?

Battery life should increase. Because we have 4 cores, we can run them on lower voltages. So overall, our plans are, and we expect to have better battery life.

http://www.youtube.com/watch?v=qhDmQCOyXrU

The power consumption and battery life should be akin to the Tegra 2.