Ordering of boolean values

Under C++ or <stdbool.h> from C99, how is the less-than operator < defined for boolean values?

Alternatively, explain the behaviour of this code:

#ifndef __cplusplus
#include <stdbool.h>
#endif
#include <stdio.h>

int main() {
    bool b = -1;
    if(b < true) {
        printf("b < true\n");
    }
    if(b < false) {
        printf("b < false\n");
    }
    if(true < false) {
        printf("true < false\n");
    }
    if(false < true) {
        printf("false < true\n");
    }
}

Under MSVC version 10, compiled as C++ code, GCC 4.6.3-ubuntu5 compiled as C code and G++ 4.6.3-1ubuntu5 compiled as C++ code, all you get is

false < true

That is, the following inequalities are all false:

(bool)-1 < true
(bool)-1 < false
true < false

And the following is true:

false < true