I only noticed today that Bluetooth was switched on, on my ipad2, and I thought I had it switched off before updating to IOS5, so check for that. It is worth checking that your iPad doesn't have some of the other higher drain things on, like 3G if you don't need it, and location services ( you can switch on or off just the ones you need at this time). Set screen brightness to auto, or reduce it to low and opt to have emails manually set to download instead of constantly being pushed to your ipad to improve battery life.