pythonCascade is going to be a complete Python wrapper for Open CASCADE, one of the three major modeling kernels available on the market today http://www.pythonizer.org/pythoncascade/pythoncascade.html
MayaVi A library and application for scientific visualization based on VTK.
OpenEXR for loading and saving images in ILM's OpenEXR format
Charts and plotting:
GR Framework - a framework for scientific visualization
libploticus (Python wrap for Ploticus) seems not to be mentioned elsewhere
PyX (http://Pyx.SourceForge.net) - Python graphics package generates EPS
See also SciComp plotting