To get the Motorola Xoom Wifi Android 3.1 update for you device, you don't have to dive into rooting and stuff. Go the easy way. That's how I got the update. Please follow these steps:
1. Register at motorola's website.
2. Register your Motorola xoom on the website (your IMEI is your Mac address without the ":" separator).
3. Update your personal information because when you register you don't input your full address.
4. Wait for a little while (I didn't say minutes, but you will get soon eventually).
5. The update may pop-up on your screen, click "install". Download the update, it takes minutes to download.
6. Your device will reboot, and the update process will take 10 ~ 15 minutes. The first reboot after the update finishes takes along time, patience is good.
7. Enjoy your new update.
Sent from my Xoom using DroidForums