Along with iOS 5 Apple has added OTA (over-the-air) operating system updates. This means smaller, targeted updates can be downloaded directly to the iPad instead of dealing with large IPSW files on iTunes. Only the parts of iOS that need to be improved are downloaded and replaced.
To update the iPad OTA, iOS 5.0 or later must already be installed. The iPad battery must be at least 50 percent charged or the tablet should be plugged in before starting the OTA update process.
Follow these steps to update the iPad operating system OTA:
1. Connect the iPad to a Wi-Fi network
2. Select Settings -> General -> Software Update
3. The iPad checks for iOS updates from Apple
4. After the available update appears touch Download and Install
5. Agree to Terms and Conditions
6. After the iOS download and installation finishes your iPad will reboot
Now your iPad is running the latest iOS version, without having to connect to iTunes on the computer.