I had some problems with python and universal builds related to the
WORDS_BIGENDIAN macro. Because universal builds are built in one pass
(one configure), the AC_C_ENDIAN cannot be used reliably. Example:

int main()
{
#ifdef WORDS_BIGENDIAN
    printf("Big endian macro defined\n");
#else
    printf("No big endian macro defined\n");
#endif

    return 0;
}

If I build this against python 2.5, it prints no big endian macro (I
have an intel CPU), as expected. But with python 2.6.0 (official binary
from python.org), I get Big endian macro defined.