A quick and easy way to have your environment variables set up properly in Mac OS X's X11- create a file in your home called .xinitrc with the following lines:

source ~/.profile
source /etc/X11/xinit/xinitrc

EDIT: That doesn't work properly at all.
The problem is that apple's X11 launches your shell as a non-login shell, which inherits a different $PATH variable. Personally i've just symlinked ~/.bashrc to ~/.profile . If you've got more complicated stuff than say paths in your .profile you'll probably need two separate files.