Update: We went back to do a little more investigation, and this thing is most definitely running Honeycomb. We were able to bring up the app pane, and saw the full suite of Google apps within. We also caught a new app switcher, which is invoked by hitting a little icon that resembles a deck of cards. Check out the UI shots in the second gallery.
Update 2: Now with video after the break!
Motorola Xoom, up close and personalSee all photos
Motorola Xoom first hands-on!See all photos
Motorola Xoom Honeycomb UI photosSee all photos