You really can't be using it much then - there is NO way that my iPhone 4S could last 24 hours without a charge on moderate usage. So either you have everything turned off or you don't use it much or you have a magic iPhone
Even Apple don't rate it that long... I am not saying I don't believe you but I have had more phones in the last 2 months than any normal person and none of them with the exception of the Titan have lasted a whole day of my usage and as excited as I am about the Nexus I expect that to be the same situation.
(for the record, iPhone 3GS, 4, 4S, HTC Sensation, Sensation XL, XE, Titan, Evo 3D, LG Optimus 3D, Nexus S, Dell Venue Pro, Samsung Omnia 7, Galaxy S II, Ace and Fit)