I'm just working on building an interface to allow admins to edit and manage the html fragments that make up a theme in the repository. Ideally, it will be a web-based solution similar to MovableType or PMachine, where you can edit fragments of HTML directly in the repository.
That does expose a risk, though. What if an admin is editing the theme managment page template, and breaks it? Doh...
I'm thinking that a separate Admin WO app (that isn't themed itself, but knows about theming and can access the database store for the HTML fragments) would be a better idea. If an admin is happy with their theme, they can kill the WO app that manages them...
Maybe even a JavaClient application to manage HTML fragments? hrm...