I'm trying the 23.2 release Cocoa Emacs build (OS X 10.6). There's a number of things that are more annoying about Cocoa Emacs than the terrific Carbon Emacs (based on an Emacs 22 build, I believe), so I hoped folks might have some solutions/thoughts (unfortunately posting on neither the carbon-emacs list nor emacs-dev has produced a useful reply, so I thought I'd try Stack Overflow for the first time):
goto-address
perhaps is what you want.
(add-hook 'find-file-hook 'goto-address-mode)