Ok, I guess there's a very slim chance it is going to happen as Rhino is designed as a nurbs modeller, but some freeform mesh modelling tools (like in Sculptris) would be awesome.

A simple brush would really do the trick. I'm working with lots of mesh data from Zbrush/Mudbox/etc artists and sometimes tweaking those to make them manufacturable is a real pain (Zbrush/Mudbox/3d Coat lack proper analysis tools to make tweaks there).