As far as I know: not exactly. You have to create a PPC binary on a PPC Mac and Intel binary on an Intel Mac. After that you can combine both executables to an Universal Binary with the lipo tool that ships with Apples Xcoder developer pack. You can use it like this:
lipo -create <new_universal> <plat_specific_bin_1> <plat_specific_bin_2>
lipo -create <new_universal> <plat_specific_bin_1> <plat_specific_bin_2>