Even though this is being presented as a rumor, it seems so damn inevitable that it's almost worth running as a "Captain Obvious" post before it's even been confirmed. Nevertheless, rumblings suggest that Sony's new handheld -- the NGP -- will max out at five hours of battery life.
This would bring it in line with the original PSP, which also boasted a notoriously short lifespan. If anything, it'd be shocking if the battery life wasn't less than four-to-five hours. All those flashy graphics, 3G, and quad-core shenanigans don't just appear by magic, unfortunately.
So yeah, even though it's a rumor, we can more or less take it as read that we won't be playing this for the duration of a non-stop flight to Japan. You don't get something this powerful without some serious energy demands.
Source: NGP battery life is 4-5 hours [Eurogamer]