This conclusion may have been posted already, but here is what I believe to be at least one of the battery related issues in iOS5.
Until last night I had not turned on iCloud back-ups, and was getting fairly good battery life to that point. I decided I was finally ready to give this a try, and so I turned it on last night to let it do its thing while charging. I never saw any indication of it backing up but honestly, I'm not sure what to look for. Suffice it to say, I assume it was working on this in the background.
This morning I unplugged (100% charge) and went to to work. Normally by lunch time and not using my phone much (mostly standby), I would be down to 97-98%. Today as I was about to go to lunch I noticed my phone was slightly warmer in my pocket than normal, so I took it out and it was down to 87%. As per my usual routine, I had no time do do anything on my phone before lunch, so this was only standby time. Assuming this was related somehow to iCloud back-ups, I disabled the feature at that point. The phone returned to a normal temp, and the battery has returned to a normal pace of battery depletion.