Lots of advice buried throughout this rather lengthy thread. But if you're upgraded to 10.8.3 and are still having trouble (or if trouble just found you), then be sure to try the following:
1. Download Onyx and clean out everything (mostly User and System caches). Also repair permissions.
2. Reset SMC and PRAM.
3. Reinstall 10.8.3 Combo pack
4. Turn off iCloud and turn off the Notifications
5. Recheck to see if problem is still there.
6. If not cured, check the Battery's Current Max Capacity to see if it is dropping between charges
7. If it isn't not dropping, you can decide to stay on ML or downgrade to SL or Lion, depending on where you came from. Your choice, really.
8. If it is dropping, then downgrade to SL or Lion, depending on where you came from.
9. If you came with ML or you just want to do so, take it to an Apple Store.
At this point, I think the problem is configuration related (mostly) and another problem with the sleep rountine. Sometimes steps 1 through 3 helps with configuration, but NOT consistently. Some people have had success doing a clean install, although again, NOT consistently.
But, be warned, if you are getting poor performancing (e.g., dropping 1% every minute or two) it might not only be affecting your battery life (how much time remaining in a charge) but could affect your battery health (how much capacity when fully charged).