What does the default /etc/profile on Mac OS X 10.8 look like?

Contents on OS X 10.8.3 from Apple's Open Source web site:

# System-wide .profile for sh(1)

if [ -x /usr/libexec/path_helper ]; then
        eval `/usr/libexec/path_helper -s`
fi

if [ "${BASH-no}" != "no" ]; then
        [ -r /etc/bashrc ] && . /etc/bashrc
fi

For a more general solution (or when you don't find it on opensource.apple.com), you can use Pacifist: It allows you to open the OS installer package on the OS X 10.8 DVD or disk image (InstallESD.dmg, part of the App Store download) and reinstall single files from these packages.

Pacifist Screenshot