Chaco is a platform independent plotting library for Python developed by Enthought, Inc. for the Space Telescope Science Institute (STScI) and licensed under a BSD style open source license.
http://www.scipy.org/site_content/chaco
Chaco's goal is to produce presentation quality scientific 2D graphics on a variety of output devices. The initial targets are WxPython, TkInter, Mac OS X, and PDF for hard copy output.