There are two options for finding your iPad’s Unique Device Identifier (UDID). The easiest way is if you are synced to iTunes. Simply click on the device’s name in the left hand navigation in your iTunes application on your computer. When your iPad’s basic information shows up, click on the serial number and it will change its display to the iPad’s UDID. You can then copy and paste that information in your iPad notes or record it anywhere else for easy access in case you need it when you are not at your computer.

If you are not synced to iTunes, or you want to be able to access your iPad’s UDID from your device without having to wait until you are at your computer, you can download a variety of apps that will find this information for you. You can find a UDID identifier app at the Apple App store. If you use one that has email options, make sure your email shows up in the “to” field before choosing “send” to make sure your UDID isn’t emailed to anyone else.

Resource: Howto.Cnet