I get at least 3 hours out of my N800. I almost never plug it in; I always run on batteries, and I use it constantly. I was on a jog for almost 3 hours today, listening to mp3s on my N800, and didn't run out of batteries.

50% more than a Thinkpad is a significant amount. 300% is even more, if you adopt the 1 hr vs 3 hours comparison, depending on how you use the statistics!