I'm happy to announce a new subproject of LLVM: "libc++". libc++ is an implementation of the C++ Standard Library, with a focus on standards compliance, highly efficient generated code, and with an aim to support C++'0x when the standard is ratified. libc++ is written and maintained by Howard Hinnant, but we look forward to contributions from the LLVM community.
libc++ is approximately 85% complete at this point (including C++'0x features), and while it is intended to support and complement the Clang++ compiler, it can be ported to work with a broad variety of different C++ compilers. For more information, see the http://libcxx.llvm.org web page.