I am finding the same thing, we had 2 of the first iPad's and we never thought about the battery. We replaced them with 2 new iPad's and my wife and I both have noticed the battery dropping faster, it seems like it drops about 10% faster for evey 2 hours of use. So where after 5 or 6 hours we would have 50% in now has 30%.
I called Apple support and they checked my setting, all were good. They suggested running it down to single digits on the charge and then fully charging it, I ran down to 2% and fully charged it over night, have used it for about 2 hours today and I'm at 73%, it seems lower than the old iPad.
I used a backup from my old iPad so I could keep all my setting and preferences instead of just doing a sync as a new device, any thought if there is something that was copied from the old device that would cause this issue. How many other people used a backup instead of a clean sync to start their iPad 2? And did Apple think of this? May not be anything but I'm thinking of doing a restore and start with a clean sync to see if it helps.