Power and battery life. Nexus One has a removable 1400 mAH battery and claims up to 7 hours talktime and 250 hours standby time on a 3G network, and 6.5 hours of Internet use over Wi-Fi. iPhone 3GS with the built-in battery: 5 hours talktime, 300 hours standby on 3G; 9 hours of Wi-Fi Internet use (and users have complained that the 3GS battery life is worse than older models). TechCrunch: "all this [Nexus One] hardware bling is an energy hog." Shown: a lemon battery.
Photo credit: Hila Science Center, Pembroke Ontario, Canada