I have been using auto and lambda's in my C++ code using clang since 10.6. Since 10.8 it has only improved. If you checked a few months ago you didn't check correctly.
What Xcode version/compiller settings/C++ lib settings and OSX SDK version did you use on 10.6? I found there is no good combination. Also lambdas are supported since xcode 4.4 which was released in july...
