What I posted I a different thread:
I had this problem, both before and after ML. Apple geniuses epically failed on helping me with this and other problems.
What helped was resetting PRAM, again both before and after ML. My battery life shot up from 3-4 hours on a full charge to 7-8. Look it up on the interwebz. Do keep in mind, as another poster already mentioned, that the advertised battery life is under very specific conditions. For example, Anandtech made a distinction between light and moderate web browsing at 50% brightness, which amounted to bringing up a new website on average 15 seconds faster IIRC for the latter. This small change, over the course of hours, will have a significant effect on battery life. I roll with like four squares of briughtness usually. Also, expect to get less battery life in Windows 7 under bootcamp because, according to another thread, Windows 7 will always and only use the dedicated Nvidia GPU and doesn't do dynamic switching.
Speaking of which, look up this app called gfxcardstatus or something. It'll put an icon on your menu bar that shows you, by showing an "i" for integrated or a "d" for dedicated, which GPU you're currently using. I've heard Facebook surprisingly will kick in dedicated. You can use this app to force the rMBP to only use either GPU, allow dynamic switching, and even set up preferences for when you're on/off battery for power supply. I highly recommend it since GPU usage and the screen brightness is a fairly large energy sink.
