I'm not sure where to post this, but I want to bring attention to this and I want to catch the eye of the @ipstenu @nacin and the others who guide Core.
Maybe someone can start thinking about this.
Custom Post Status is currently an underdeveloped feature in WP. These are the stages of a post for draft, pending review and so on. There are a couple of plugins, led primarily by Edit Flow that allow for the creation of custom statuses. However, either through limitations in the plugins, or WordPress itself, it is fairly restrictive.
Edit Flow, for example, allows you to create and display custom statuses and assign them to custom post types. However, it is an all or nothing deal. You create a single set of statuses the choose to assign them to your post types.
What if your individual Custom Post Types would work better with an individualized set of custom statuses?
I'm working on a project where this has come to a head. I have two custom post types: policies and bulletins. The policies CPT works well with the built-in statuses with a few modifications. But the bulletins need a completely different set of statuses. Currently, WP and the various plugins, only allow for a single set of statuses.
I propose that statuses, if possible, be tied into Custom Post Types themselves and the process of setting them up becomes an optional part of the process of registering Custom Post Types. The limitations of statuses really show their head when you start having installations with multiple Custom Post Types for different topics or needs.
If someone knows a better way to do this currently, I'm all ears. But what I've found so far in my research only points to the limitations of statuses as they currently exist. They need more flexibility and a common sense approach would be to integrate them more deeply into Custom Post Types.