Did you know that LLVM has a GCC 4.0 compatible C++ front-end and a great 
optimizer?  We find that LLVM is able to compile C++ into substantially better
code than GCC (for example).  Also, because LLVM code can be converted to C,
you can even use LLVM as a <a href="http://lists.llvm.org/pipermail/llvm-dev/2004-June/001380.html">C++-to-C translator</a>.