well they've only annouced Talk time/video/web browsing and the 16hours of music.. they haven't released info on stand by time.
"Up to 16 hours of battery life refers to music playback. Up to 5 hours of battery life is based on H.264 1.5-Mbps video at 640-by-480 resolution combined with 128-Kbps audio. Rechargeable batteries have a limited number of charge cycles and may eventually need to be replaced. Battery life and number of charge cycles vary by use and settings. See www.apple.com/batteries for more information."
for more info on the specs check out
I have a regular phone with over 48 hours battery life.
I don't know about smart phones, but I don't want one that lasts only 5 hours before running out.