zxSet 0.1 is available here: http://sourceforge.net/projects/zxpy/
zxSet is a Java implementation of the standard Python distribution's sets module until such time as Jython supports new style classes.
It passes all but two of the test_sets.py unit tests: (1) Pickling operator.add (2) A string on the left hand side of an 'in' neither of which is really related to the set operations.
It has only been tested with the current CVS version of Jython since it makes use of the iterator protocol not available in Jython 2.1.
Feel free to contact me with any comments, suggestions, questions or complaints.
brian zimmer, (firstname.lastname@example.org)