What's a good IDE for Python on Mac OS X?

My 2 pennies, check out PyCharm http://www.jetbrains.com/pycharm/

(also multi-platform)

Have tried many different (Kate, Eclipse, Scite, Vim, Komodo): each one have some glitches, either limited functions, or slow and unresponsive. Final choice after many years: Emacs + ropemacs + flymake. Rope project file open dialog is extremely quick. Rope refactoring and code assist functions are super helpful. Flymake shows syntax mistakes. Emacs is the most configurable editor. I am very happy with this config. Python related part of config is here: public.halogen-dg.com browser/alex-emacs-settings/configs/cfg_python.el

I use TextMate for all my Python programming needs. It's not an IDE per se, but it does a lot of stuff that an IDE does (without all the cruft of an IDE). It has syntax highlighting, code folding, integration with various SCMs through the use of additional bundles (I know it supports SVN, Git, Mercurial, Darcs, and probably a few others). It's also quite extensible and customizable (again, through the use of bundles). It also has a basic concept of projects. One place where it doesn't shine, though, is in code completion; some bundles have limited support for code completion, but it's generally not as amazing as that of most language-specific IDEs. Given how awesome TextMate is, though, I don't know sacrificing that. TextMate's definitely made me much more productive.