I have the Wifi model of the Xoom that I bought online a while ago. I am in the US and I have been anticipating the ics ota update. I was looking in Settings > About tablet when I noticed that my Xoom had a build number that was not for the US. So I followed the instructions here:
And I downloaded the US build and unlocked the Xoom, installed it, and relocked it.
I received the ota 3.1 update and it downloaded, but when the Xoom restarted to install the update it stopped mid-installation and the android guy was sitting there with the yellow caution sign.