Not all 10-speed hubs can. The loose-bearing Shimano hubs (Tiagra - Dura Ace) can, but many other hubs are too narrow to take anything but 10-spd. I was unable to run 9-spd on a set of AC Sprint 350s, for example -- and I know the Dura-Ace wheelset has a 10-spd-only freehub body as well.