Well, it's actually not broken much, yet. The std::string and std::list classes are still not C++11 conformant right now, and fixing that will certainly cause ABI issues.
Since the change to std::list in C++11 mode was reverted (it was incompatible in 4.7.0 and 4.7.1, reverted in 4.7.2), I've been using C++11 code against C++98 libraries without a problem.