Many celebrities are aware of the potential benefits and pitfalls of CGI these days, and have trademarked their likenesses to discourage unauthorized usage.

Poser users have, of course, been creating celebrity lookalikes for years, but DAZ set an interesting new precedent in the Poser community recently by licensing supermodel Anna-Marie Goddard's likeness for its first Digital Clone product.

Renderosity has a copyright forum, as does DAZ. Someone there can probably provide a detailed explanation of the legal ramifications.