The Polygon library has both a rotate and scale function. http://www.cs.man.ac.uk/~toby/alan/software/ http://en.wikipedia.org/wiki/General_Polygon_Clipper
I've used it for my thesis work and found it to work fine. The only problem is that you need to write something to convert from your current format to the gpc format and back. I have written conversion functions for OGR and PySAL if you're interested. Daniel
