Django on Jython
When I write about Python I'm almost always writing about "C Python", the Python interpreter and extension modules written in C and executed in the C runtime environment. The first alternative was "Java Python" or Jython, which is written in Java and executes in a JVM. It's author, Jim Hugunin, switched to working on IronPython (.NET), and it stalled for a while before reemerging last year under the sponsorship of Sun. The Jython team has been using Django, one of Python's highest profile applications, as a development target and have reached a major milestone.
I don't know enough about Java web app deployment to comment on the usefulness of this (Using Tomcat to run Django when you could just run it under mod_wsgi?) other than to get more direct access to Java libraries like Lucene, but it certainly inspires confidence in Jython. I could see Shapely or GeoDjango adapted to Jython to bring some geoprocessing power to the framework. Each are currently based on GEOS, which is acknowledged to suffer in translation from Java to C++. Jython versions based instead on JTS would have more features and better performance.
Via Sean McGrath.