The Python community has a long history of April Fool's postings to news:comp.lang.python (a.k.a. mailto:python-list@python.org). We've collected references to a number of them here. If you know of more, please update the page.
[http://mail.python.org/pipermail/python-list/2001-April/076593.html 2001 - PythonLabs team moves to ActiveState]
[http://web.archive.org/web/20071201071244/http://www.python.org/parrot.html Python and Perl joint development]
[http://mail.python.org/pipermail/python-list/2003-April/197232.html 2003 - Stackless Perl 4.0]
[http://mail.python.org/pipermail/python-list/2004-April/256320.html 2004 - 'goto' for Python (which actually works!)]
[http://mail.python.org/pipermail/python-list/2005-April/315453.html 2005 - Perl-to-Python translation review request]
[http://mail.python.org/pipermail/python-list/2006-April/375866.html 2006 - Python to adopt royalty-based commercial licensing]