The next release of PCL will include two new components: PCL-Spatial, and PCL-Data, industrial-strength geometries and an agile feature model for Python programmers. I'm going to write about geometries today, and about the feature model in a day or two.
PCL-Spatial is a Python package that wraps and extends GEOS. The Geometry Engine - Open Source is a C++ port of Vivid Solutions' Java Topology Suite, and is the open source C/C++ library for spatial predicates and geometric operations. It's used in GDAL, MapServer, and MapGuide Open Source, to name a few applications, and Safe Software and Autodesk are funding work that will eventually produce a GEOS 3.0 release.
Why not use one of the existing Python geometry modules? Good question. The short answer is that none of them are quite good enough. Everything out there right now comes up a bit short in capability, usability, or portability.