Major Neslon has cleared it up...somewhat.
"We know there is some confusion around used games on Xbox One and wanted to provide a bit of clarification on exactly what we’ve confirmed today. While there have been many potential scenarios discussed, today we have only confirmed that we designed Xbox One to enable our customers to trade in and resell games at retail. "
"Beyond that, we have not confirmed any specific scenarios.
Another piece of clarification around playing games at a friend’s house – should you choose to play your game at your friend’s house, there is no fee to play that game while you are signed in to your profile."
This ultimately doesn't bother me, because once we make the final transition to no discs all digital content, there won't be any reselling of games at all. You don't go trade in games you buy on Steam any more than you can trade in music you buy on iTunes, and that is where we're headed. This is part of that step towards the disc-less future.