>Of late the libertarians in this country have decided even that shouldn't be, although the Constitution limits most acts of sabotage against it.

Yah, conservatives have done their best to try and destroy it for the past two decades, and thank god their options for interference are somewhat limited. In any event, when you cut through the bullshit, the USPS basically costs almost nothing (on a net operating basis), and still provides all the valuable services that the framers intended (and several more).