Last week I spent a huge amount of time getting the general interface of the relationship editor working: adding, removing, and changing relationships, along with the associated dialogs to do this.
Nothing can be submitted yet, but that's what I'm focusing on this week.
The UI in general took quite a bit longer than expected, because there were so many problems that occurred when an entity or relationship appeared more than once on the release. For example, some releases have duplicate recordings; even more have different recordings of the same work. When the user changes a relationship attached to one of these entities, it should change everywhere else it appears on the page.
The obvious missing features right now are batch relationship-adding/editing, batch work-creation, and release relationships.
The current progress is viewable at http://bitmap.mbsandbox.org/ - I try to keep this server running at all times, but keep in mind it's my development server, so it may not always work. The relationship editor is accesible from the the "Edit Relationships" tab on any release page.