Descartes is done. What's it for? Appealing precision plotting of polygons resulting from analysis of spatial data, holes and all. Examples of using it to produce figures for the Shapely manual are at http://github.com/sgillies/shapely/tree/master/docs/code/. The figures seem to be working:
Sean Gillies has just finished documenting the Shapely a “Python package for manipulation and analysis of planar geometries.”
The first impression you get is that its attractive. The images of geometry (generated by the Python package descartes) catch the eye, and it was these images as much as anything else that led me to trying Shapely in the first place.
That pleases me, though it's really matplotlib (and the Agg backend) that make the figures shine. Descartes just makes it simple to plug in GIS type data. The Shapely manual is not quite finished, but closer every day.
Related: Martin, I heart JTS too.