Portable Package Formats
I just wanted to mention that the GNOME developers have also been working on such a thing and I first became aware of it back in March when I watched the video What are we breaking now? by Lennart Poettering, Kay Sievers and Harald Hoyer. The talk about App packaging starts around 38:20.
In a Google + comment (not sure how to link to it), KDE's Aaron Seigo mentioned that KDE had pioneered a similar concept but I'm not sure what he was referring to. Maybe it was for the tablet-flavor of KDE he has been working hard on?
There is a lot of scepticism about the need for a new packaging format but everyone working on it seems to be pretty smart so I'm guessing they have good reasons. Just to clarify, no one is talking about trying to replace the underlying distro packaging system.