There are a few artists over in Weta Digital that swear it is. Designed by artists, for artists. There’ll be a demo of it at the Montreal Artists Workshop.
“Mudbox is a friendly sculpting, detailing, and design tool developed by three experienced cg artists, a group of whiz programmers, and a beta team composed of some of the planet’s top vfx and gaming production companies and artists. It’s a standalone application that, in our experience, slides smoothly into company pipelines and artist workflows.”