A few days ago we reported that Google is looking into optimizing Google Voice to run on the Motorola Xoom, and Honeycomb in particular, but that just wasn't good enough for Android Central forums member Elysian893. The fact that it wouldn't work was enough to get them thinking, and look for a way to fix the issue. With the use of their Droid and Titanium backup they installed Google Voice on the Droid, backed up the application and settings and then restored it on the Xoom.
Upon first launch it force closed, once permissions were granted for it to access the Google account, it launched perfectly. While you can't quite use the Xoom to make calls, you can still use it for SMS, or use it to call through another device. If you are interested in getting Google Voice running on your Xoom, be sure to check it out. Takes a couple steps, but it gets the job done. [Android Central Forums]