Do you maintain an application that people use? Do you want people to be able to install it easily in the GNOME Software Center?
If both of those are true, please read the newly finalised AppData specification and ship one tiny extra file in your tarball. People will love you for doing it, and I’ll really appreciate it. Maybe post 3.10 we can do a GNOME Goal for all the core GNOME modules, but of course this applies to GNOME, KDE, XFCE and random standalone apps.