And like you mention, doing multilib on other platforms needs "lib64". (at least I think it would, as I am not running any 64-bit just yet)
On second thought, we don't need any /opt/local/lib/{lib32,lib64} or multilib on other platforms - just one native "lib" directory. Just because the system has /usr/lib/lib32 and /usr/lib/lib64 for compatibility, doesn't mean one has to compile using it... Then again, I said the same thing about Universal Binaries too. So maybe MP does "need" multilib, like it "needed" +universal ? But compiling 64-bit binaries on a 64-bit system, _that_ is at least a often required feature and thus it should be supported. --anders PS. http://www.redhat.com/magazine/009jul05/features/multilib/ (on Darwin this is all handled by using the fat binaries)