Honestly, i could definitely see them doing this but im fairly positive that they just mean that it'll just be like when you turn off your 360 with a background download going. Its still online, but off. Itll be like that but all the time. Never completely turns off. Like that, you could even queue downloads from your phone, their site and whatnot, and not have to wait to get home, turn on your xbox, and have the download start. This way your be able to literally queue downloads at anytime, anywhere and it will start instantly regardless. I definitely see this as a possibility from them.
edit: And add to that how they want games to be installed, well now, this gives them the possibility to update your games instantly whenever they want. Go in, boot up the console, boom, notifications telling you "your game as been updated" or just new dlc maps, new sp levels are now available in such and such game, already installed, just waiting for you.