Carol Barnhart Inc. v. Economy Cover Corp.
773 F.2d 411 (2d Cir. 1985) - full text opinion
The court contrasts the torso forms in this case with the belt buckles in Kieselstein-Cord v. Accessories by Pearl, Inc. in finding that the torsos are completely utilitarian in function, and have no creative element that can be copyrighted.
And, even if moldings and mannequins aren't creative*, artists, especially the Dadaists, have found them to be a fertile medium of expression.
If you've ever felt nervous or scared around mannequins, don't worry, you're not alone. Lots of people suffer from automatonophobia.
* Recently, the 7th circuit ruled in Pivot Point International Inc. v. Charlene Products Inc. that mannequins can have features separate from its utilitarian function, and therefore, can be copyrighted.