Mac OS X is no longer supported via Carbon. Use the NeXTSTEP port, described above.
A NeXTSTEP port, a.k.a. "Cocoa support".
And, meanwhile, the Carbon Emacs guy reports that he doesn't plan to release an Emacs 23 version of Carbon Emacs in 2009:
http://groups.google.com/group/carbon-emacs/browse_thread/th...
Perhaps the time has finally come to try rolling my own emacs from source. That will require a Great Package Hunt in the short term, but once you've got emacs set up you've really got emacs set up. It's not like it changes every weekend.