Apple just released an update to iOS 5, version 5.0.1, is now live for download. The update fixes the software bugs that caused several iPhone 4S owners to suffer from horrible battery life.
The update is available over the air, meaning there’s no need to sync your iPhone or iPad to your computer to get it.
Just go to Settings > General > Software Update.
If your iDevice doesn’t recognize the update right away, wait a few minutes and try again.
Also note that the download may be slow since there are likely a ton of people trying to get the update at the same time. Be patient, and plug your phone into a power source so it doesn’t die while it’s trying to update