Xcode is now a self-contained application bundle which confuses CMake.
The CMake git repo contains necessary fixes but those haven't been incorporated into a new CMake release yet so to use those you have to build the cmake command line tool yourself by
The project generation command I (Mortimer) used was `cmake -G Xcode -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++`, obviously specifying clang as the compiler. There is a related CMake option called USE_APPLE_CLANG which should be ON by default.
After that I had a proper Xcode 4.3 project.
To use the CMake GUI for setting some library paths I put the self-built cmake command from /usr/local/bin into CMake 2.8-7.app/Contents/bin/ but one could have probably done that by editing CMakeCache.txt or setting via however the cli syntax for setting variables is.