This aspect of a papal retirement didn't hit me until I heard talk of this over the weekend; we've never had a former Pope before(not in more than half a Millenium.  Nor did I consider the potential practical affect of this meaning there are "Two Popes." The Vactican is downplaying any possible friction. But I think whether that's an issue depends on who the new Pope is and how his philosphy conflicts with Benedict's.