[boost] intrusive_ptr question

The intrusive_ptr contains two functions that allow comparisons between intrusive_ptr<T> and T *. template<class T> bool operator==(intrusive_ptr<T> const & a, T * b); template<class T> bool operator==(T * b, intrusive_ptr<T> const & b); and similar operator!=() functions. I'm curious why the pointer parameters are of type T* and not T const *. Joe Gottman