List of python developers and users on http://twitter.com
Guido van Rossum http://twitter.com/gvanrossum
Michael Foord http://twitter.com/voidspace
James Tauber http://twitter.com/jtauber
Ted Leung http://twitter.com/twleung
Doug Hellmann http://twitter.com/doughellmann
Andrew M. Kuchling http://twitter.com/akuchling
David Stanek http://twitter.com/dstanek
Augusto Becciu http://twitter.com/abecciu
Skip Montanaro http://twitter.com/skipmontanaro (though I don't really know why)
Fred Drake http://twitter.com/freddrake
Georg Brandl http://twitter.com/birkenfeld
Armin Ronacher http://twitter.com/mitsuhiko
Juergen Brendel http://twitter.com/BrendelConsult
List of usergroups and python related events:
pycon http://twitter.com/pycon
Portland Python UG http://twitter.com/pdxpython
Tucson Python UG http://twitter.com/TuPLE
I started the list as a response to http://rubylearning.com/blog/2008/10/29/50-rubyists-to-follow-on-twitter/. Feel free to add python developers or yourself if you tweet about python -- http://twitter.com/peterhoffmann