Why is iOS 5 draining my battery so fast? My wife's phone went from lasting a full day to needing a recharge every few hours after upgrading to iOS 5.   Mine still works fine after the upgrade.  What might be causing this?
I think I've found the answer for my case. Location services were completely innocent, and I've returned them to default settings. My phone synchronises with a Zimbra server, set up as an Exchange account. The update enabled sync of Reminders, but the Reminder sync didn't work. Removing Reminder sync from the Exchange account setup has stopped the battery level dropping while I watch.

My general advice is to check your mail accounts to see if anything new is being synchronised, and then disable it if you're not using it.

Edit: added image showing Reminders control.