I've had it happen once. I just hard booted the phone and they came back. As much as I use my nexus, for it to only happen once since release day is acceptable for me.
The only bugs with the Xoom are with the OS, so any 10.1 tab you get with 3.0 are going to have the same issues.
I got the Xoom and I have no regrets. Its an amazing piece of technology, and its just going to be amazing when its ironed out smooth.