Tip: if building a +universal variant in MacPorts (for example, because you’re trying to build and install the Python Imaging Library), then you should check /opt/local/etc/macports/macports.conf to see what MacPorts considers “Universal”:
universal_archs
The machine architectures to use for +universal variant (multiple entries must be space delimited). Options include: ppc, i386, ppc64, x86_64
Default:
x86_64 i386(ppc i386for 10.5 and earlier)
(from http://guide.macports.org/#internals.configuration-files)
On Mac OS X 10.6 (Snow Leopard), the default value for universal_archs is x86_64 i386. Note that it does not include the PowerPC architecture. This makes perfect sense, because Snow Leopard doesn’t run on PowerPCs. Unfortunately, when installing PIL with pip, it builds for PPC as well, and thus requires PPC architectures in its dependent libraries, even on 10.6. I do not know how to disable PPC support in PIL (or pip?). All of this Python extension building stuff is new to me :)
The upshot: if you are running 10.6, then you must edit macports.conf and add “ppc” to universal_archs before you follow the directions in the linked article.