Toshiba's Portégé R705-P40 manages to creep just past the 3 hour mark on our real-world rundown test. That's fairly impressive for a CPU as power-hungry as the Core i5-460M, but the IGP no doubt helps things out. We think that if you were less demanding on this, you could see 4-5 hours. But still, the 8 hour mark that Toshiba claims is possible seems a far-fetched fantasy. Even with wireless disabled and your screen brightness cranked down, we doubt you could get this unit to last a full 8 hours. Still, the battery life here is fairly average for the size, and considering that you're getting above-average performance, that's a pretty fair tradeoff.
The 6-cell battery is also pretty slim. There's no bulge from the rear, and it's able to be removed and swapped out by the user. If you really need this machine to last through an intercontinental flight, you should deifnitely pick up a second battery.