While it's possible to get root on the Xoom by unlocking, flashing a recovery, and then flashing the Xoom-Universal-Root.zip, apparently it is also possible to do via the same procedure but instead flashing a recent Superuser.zip. (Older versions of Superuser are here.) Unpacking those zip files, Superuser.zip seems basically a subset of Xoom-Universal-Root.zip. I am not clear what additional capabilities we get by approaching root this way. If anyone knows, I'd appreciate being enlightened.