The Python community celebrated April Fools' Day, too (even though they were rather easy to figure out, I liked them for their creativity):

"Trying to get PyPy to run on Python 3.0" <http://morepypy.blogspot.com/2008/04/trying-to-get-pypy-to-r...; If you followed PyPy's politics in the last few months, the headline's already yelling "APRIL FOOL" at you. I liked the "Automatic Program Reversion on Intermediate Languages" (APRIL). ;-)

"psychotic -- Pure Python code optimizer" <http://code.google.com/p/psychotic/>; The source is definitively worth a view.