since you use only pointers to the other class your case is rather simple. just put a forward declaration to class foo into boo.h
Code:
//FILE - boo.h
#ifndef BOO_H
#define BOO_H
#include "foo.h"
class foo;
class boo
{
  public:
    boo();
    foo* getFoo();
};
#endif
It's a bit more difficult if you want to ebbed an object of the other class in one of the classes because then everything depends on the order of the inludes in the implementation files-
Kurt