C-h is correctly interpreted has 'help' in Carbon Emacs.app and using /usr/bin/emacs in Terminal.app. I'm sure I'm missing something simple here. Emacs describe-bindings shows c-h is rightly mapped to help. So it seems like xterm or X11 sees a c-h keypress and then sends a backspace to emacs. Can this behavior be changed?
Found the solution here: http://www.ibb.net/~anne/keyboard/keyboard.html#Xterm
Apply palm, with force, to forehead.
Many thanks to those that responded.