PyOpenCL lets you access the OpenCL parallel computation API from Python. Here's what sets PyOpenCL apart:
See the PyOpenCL Documentation.
Having trouble with PyOpenCL? First, you may want to check the PyOpenCL Wiki. If that doesn't help, maybe the nice people on the PyOpenCL mailing list can.
Or get it directly from my source code repository by typing
git clone http://git.tiker.net/trees/pyopencl.git
You may also browse the source.
Prerequisites: All you need is an OpenCL implementation. And Python obviously.
Pydgeon is a simple GPU-based discontinuous Galerkin code loosely based on the MATLAB codes from the DG textbook by Jan Hesthaven and Tim Warburton.
For more information see the wiki page.
Like last year, I had the honor of being invited to present PyCUDA and PyOpenCL along with a few examples of their use to a great crowd at Nvidia's inaugural GPU Technology Conference 2010.

Please click the following link to view the slides: pycuda-pyopencl-gtc-2010.pdf.
Update: Nvidia has posted a recording of the session. There's also a full list of sessions, with many talks that are worth being watched. In particular, I'd like to recommend the ones by Bryan Catanzaro on Copperhead, which is built on top of PyCUDA, by Tim Warburton on all things GPU-based discontinuous Galerkin. Also check out the poster on Atomic Hedgehog by Cyrus Omar.
This past week, I had the honor of presenting a talk on PyCUDA at Nvidia's inaugural GPU Technology Conference.

Please click the following link to view the slides: pycuda-nvidia.pdf.
Update: Nvidia has posted a recording of the session that you may watch or download.
Update 2: Giancarlo Colasante has transcoded the above video into just 16 MB. You may download the resulting video here.