I'm on a slow n/w connection this weekend... please give me a couple of days to check this out.
(global-unset-key (quote [ns-power-off])) ; prevent 'aqua'/'ns' prompt-related crashes on exit
(global-unset-key (quote [(menu-bar) file exit-emacs])) ; prevent 'aqua'/'ns' prompt-related crashes on exit
http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=3979
I checked in external function declaration in nsfns.m on 2009-08-21 that fixed a related crash (bug #2154) on Leopard/PPC. If you haven't checked this since then could you please see if the issue still exists?