A new LLVM/Clang has been released, with even better C++11 support. Sadly, no important Windows specific things were fixed or added since the previous release (that I know of), so you're still limited to GCC 4.6.3's libstdc++.
The previous 4.6.3 GCC linux64 build was also incompatible with older Linux installs, like Debian stable. This one is buillt on Debian stable, so should work on any non-ancient Linux install. If you need older or 32-bit linux, download the source package and build it yourself :)