During our testing (shown above in minutes), we found the battery life of the machine to be somewhat underwhelming, but not embarrassingly so. With performance mode enabled (meaning that the discrete GPU was activated to assist the integrated set), we squeezed out just under 1.5 hours before Vista forced itself into hibernation. With Power Saving mode activated (which disables the Hybrid SLI system and uses the integrated GPU alone), we were able to get just under 2.5 hours of life.
Mind you, this test represents "normal" activity. Light web surfing, MP3 usage, typing, etc. -- if you did absolutely nothing else, we wouldn't be surprised to see the battery hold up for three hours. 2 hours and 21 minutes isn't awful for an ultraportable, but it's certainly not inspiring. If you think you'll need more than that per sitting, go ahead and invest in an additional 9-cell to pack alongside the stock 6-cell.