A tweet by Motorola just a minute ago:
Motorola XOOM update rolling out in phases starting tonight & includes required enhancements to support upcoming Adobe® Flash® Player 10.2.
Update:
This is from the support forums at Motorola from the Forum Manager:
We are happy to announce that an over-the-air update to the Motorola XOOM software will start rolling out in phases tonight to all Motroola XOOM owners on the Verizon Wireless network.
You can receive the update over a 3G or a WiFi connection. If you are not connected via WiFi or 3G, or your Motorola XOOM is off when the notification arrives, you will see the notification when you next connect to a wireless network.
If you have unlocked/rooted your Motorola XOOM, you must restore it to the standard software load and relock your device to receive the notification.
Owners who have unlocked/rooted can manually download the file and follow the instructions here:
How to: Manually Update Motorola XOOM to HRI66 (Android 3.0.1)