Because as a baseline, OMAP3 is reasonably comparable consumption-wise to OMAP2. At the lowest end it'll use significantly less (matter of scales, mostly, as naught isn't that much smaller than ought ), while at the top end it'll use slightly more (PowerVR, ISP added on).

Throw in a bunch of extras like GSM, accelerometers and FM radios, and you've pretty nicely eliminated the power advantage offered by the reduction in screen size.

So, yeah, I'd say it's safe to assume that battery life is going to be worse. Yet more hardware idiocy by Nokia (that "kickstand" is going to suck) . . . bleed the enthusiasm out, Nokia, bleed it out.