What differences, if any, between C++03 and C++11 can be detected at run-time?

Question

It is possible to write a function, which, when compiled with a C compiler will return 0, and when compiled with a C++ compiler, will return 1 (the trivial sulution with

Answer 1

This isn't quite a correct example, but it's an interesting example that can distinguish C vs. C++0x (it's invalid C++03 though):

 int IsCxx03()
 {
   auto x = (int *)0;
   return ((int)(x+1) != 1);
}