What breaking changes are introduced in C++11?

Question

I know that at least one of the changes in C++11 that will cause some old code to stop compiling: the introduction of explicit operator bool() in the standard l

Answer 1

There are numerous changes to the containers library that allow more efficient code but silently break backwards compatibility for a few corner cases.

Consider, for example, std::vector, default construction, C++0x, and breaking changes.