UVMapper 3 and above, IIRC. Lets you assign smoothing angle by material which in turn translates into poser, I know this is a feature simply because of reading various things here and there (I'm an obsessive tutorial and documentation reader)... In terms of using UVMapper myself, I'm a Mac user so I use the limited functionality classic version; which is still mighty useful... particularly for cleaning up or organization tasks, generating optimized .obj files, and creating nice templates.

I always use control loops or edges to deal with Poser autosmoothing, sure it makes your model heavier but there's no splitting involved and it makes the model hassel free out of the box without a lot of fiddling around with angle or smoothing settings for the end user. For UVMapping, depending on the object I use UVMapper classic, Wings, and Carrara 8 pro and usually a combination of all of the above. I have an idiosyncratic workflow I guess.