This is a little old but I haven't seen it mentioned here. The story is this. Last week a Reddit user posted screen shots of a Lumia 920 he bought on EBay. That phone turned out to be a developer device that should not have been sold. Among the apps on the phones app list was one named zCortanaApp. Microsoft has since purchased back the phone.

It makes sense that Microsoft would want to expand Halo beyond Xbox. Particularly with the soon arriving Halo: Spartan Assault. Halo is kind of a big deal for them. While I would be surprised by this if they did release such an app or include it in a future release of Windows Phone, I suppose its not completely unexpected.

Anyway, I just thought I'd throw this out there for discussion.