With LLVM/Clang 3.2, the C-Ray multi-threaded ray-tracing performance now matches that of the modern GCC compiler.
It will be nice when LLVM/Clang supports OpenMP...
The LLVM/Clang 3.2 compiler is becoming more competitive with GCC, but there are still cases where GCC remains much faster (not counting LLVM's lack of OpenMP support) and then in other workloads Clang is a strong winner. The DragonEgg plug-in performance was mixed with no really strong edge. DragonEgg will be nice if you wish to use LLVM for languages where there is no native LLVM compiler front-end but is supported by GCC, but outside of that there isn't too much value at this time.
LLVM/Clang 3.2 and DragonEgg 3.2 are expected to be released in mid-December while GCC 4.8 will be officially released around March of next year.