Hrm.  Yes, and no, to several above comments.  I'm actually not so sure about how Poser 6 and Firefly does their new smoothing, but I've experienced in various models in various renders that although a cylindrical or spherical surface may appear smooth as silk, the edge -- and shadows -- give it away with ugly facets.

My feeling is that it is wortwhile putting sufficient polygons in any curving surface to make a smooth edge at the like render resolution.  As such things go, I don't think it adds so greatly to the polygon count as to make the models implausible.

(I may think second of that once the highly-detailed drum kit I'm working on passes the 20 meg download size!)