#include <iostream>
#include <boost/thread.hpp>

void f()
{ for (;;) std::cout << "ぬるぽ" << std::endl; }

void g()
{ for (;;) std::cout << "ｶﾞｯ" << std::endl; }

int main()
{
    boost::thread th1(&f);
    boost::thread th2(&g);

    th1.join();
    th2.join();

    return 0;
}

VC7.1
結果:激しくsynchronized