What about the Emacs 22 pretests?
Emacs 22 has had several pretest releases by now, and all the major free operating systems (with the exception of SuSE) have some offerings of emacs-snapshot-gtk or similar packages.
Those snapshots/pretests are the preferred platform for AUCTeX, and in particular for W32 and MacOSX beat the pants off the "stable" Emacs 21.
But even under X11, they are in general quite more bug-free and usable than Emacs 21.
The emacs wiki is indispensible
> Do navigate to the emacs wiki.
> Let the power and simplicity entice.
OS X Carbon build available
For Mac OS X users you can now get a native app bundle with menus, syntax highlighting (font-lock), scrollwheel support and more. This build is from the Emacs CVS and hasn't made it into a point release yet.
More information & download... (http://mindlube.com/products/emacs/)
An open, cross-platform journaling program.
A scientific plotting package.