For the customers I'd like to have, frequently. Wes, I have no interest in getting into a dicksize flamewar. Sorry if it seemed that way. I agree there are very large set of machines out there.
Smaller systems are the norm.
If I don't understand what you do, please correct me. I'd be willing to bet that many of us are working with groups developing code that can take advantage of ten thousand or more CPU's. It's not what vendors can do now, but what is needed to support the needs of science and research.