With the ever increasing modularity of the body and the growing permeability of its boundary, "the idea of the body as an exclusive physical sanctuary of the self is coming under mounting pressure, in part due to the spectacular rise in the two-way commerce between the body and other objects." As external objects (implants, artificial or transplanted organs) are increasingly incorporated into the body, or form accessories to it (eg. earpieces and PDAs accessing wireless internet), it becomes more and more difficult to accept the significance of a rigid boundary, between self and other, along the body's surface.
"The Value of Ownership"
University of California, Berkeley.