Are you trying to compare ALL windows mobile? or Just HTC devices
Blackberry storm has about the same battery life as an Omnia does with very similar settings. Its really all about the model of phone and the size of the battery that comes with that model. HTC when it comes to battery has always lacked but samsung (with exception of 1760) generally had nice battery life aswell even with a touch screen.
I would say they are about even now but its SOOOO broad of a scale its hard to measure. I would say any Windows mobile would lose a battery war with anything thats a curve and back but with the bold and Storm (havent tested the new curve) they can appear to be the same with a WinMo running on general light settings...
Hope This Helps