Ruby on Mac OS Lion is going through a bit of a rough patch, installation-wise. With Xcode 4.2, clang became the default compiler and gcc was no longer included. Unfortunately, this has caused a lot of grief for Rubyists on OS X, because for a while, MRI did not officially support compiling with clang. With the release of 1.9.3-p125, that situation has changed–clang is now officially supported–but