If you've been having problems with battery drain with iOS 5 on your device, you'll be happy to know that you can now download an update that promises to fix the problem.
You can do the update over-the-air instead of via iTunes. Go to Settings, General then Software Update to update your device.
The update is under 50MB so you need to be on the WiFi network to be able to do the update.
Apart from the battery fix, the update also addresses a security hole that was discovered by security researcher Charlie Miller.