Motorola is pushing out an update to Android 4.1.1 (JRO03H) Jelly Bean which has been reported to be overall faster and easier to read. There is on major feature that is lost and that is the ability to view Flash on the web, which Adobe does not support.
You can receive the update over a Wi-Fi connection. If you are not connected via Wi-Fi, or your Motorola Xoom is off when the notification arrives, you will see the notification when you next connect to a Wi-Fi network.