I've used Aquamacs Emacs off and on. Previous versions did not seem anywhere near as useable as Carbon builds of GNU/Emacs or buulds under under X11. This version has made a big step. In particular, it seems as though standard Emacs keybindings can be reliably used as well as many Mac-standard command keys. That goes a long way toward making Emacs much more accessible to OS X users and non-frustrating for experienced Emacs users. My experimentation with t 0.9.7 version thus far indicated that the application is stable under OS X 10.3.9.

I wonder if this will ever be migrated into the standard source code for Emacs?

One note for users of a Carbon Emacs build, you may need to check the release notes for 0.9.7 re: (setq mac-command-key-is-meta) in your .emacs.