On paper, this is the most exciting of the three propositions. If you missed the announcement, SmartGlass is an app that allows iOS, Android and Windows Mobile devices (such as tablets or smartphones) to act as a touch-screen controller for your Xbox 360.
Although at a glance SmartGlass might seem to be a hastily-constructed answer to the questions posed by the Wii U GamePad, its holistic vision far outstrips simply competing with Nintendo.
If the Xbox was conceived as a way of getting Microsoft products into the living room, then SmartGlass is the final evolution of that line of thought - an app which converges all of your wireless devices together, with your Xbox pulling the strings at the heart of it all.
It's clear that Microsoft has been building towards this for years now - both Windows 8 and the Xbox 360 dashboard have been built with touch-screen interaction in mind, and their interfaces - which today seem unwieldy - will seem second-nature once SmartGlass kicks in.
At their conference, Microsoft primarily pushed SmartGlass' multimedia capabilities - such as displaying ancillary information during films or acting as a TV remote - but it was its potential as a touch-screen Xbox controller that most caught our eye.
The Madden 13 reveal demonstrated best how SmartGlass can be used in conjunction with the traditional controller to streamline 'hardcore' gaming experiences and make them more immediate and intuitive.
While picking a football play was an arduous task with caveman analogue sticks, SmartGlass makes it quick and breezy. Simply flick to the play you want, give it a tap and - BOOM! - it's Hail Marys all round (whatever they are).
The only question is, how keen will third-party developers be to use SmartGlass to its full potential? By opening SmartGlass up to iOS and Android devices, Microsoft has ensured that SmartGlass already has a huge install base, but until developers can count on every last Xbox owner having access to a SmartGlass-compatible device, it's unlikely that anyone will use it as more than a gameplay-enhancing gimmick. Watch Dogs will be one of the first Xbox 360 games to make use of SmartGlass, but rest assured that PS3 owners are unlikely to miss out on much.
Look for SmartGlass, however, to be an absolutely integral part of the next Xbox console's design.