I think a separate RSS feed would be even better!
That's actually easier to do. Code to serialize threads to Atom doesn't lend itself well to serializing Projects. They're completely different data structures.
Alternatively we could have the code that updates a project's status create a thread that announces this status update, whether it be a new project, or a project newly marked as being in hiatus. We'll discuss it internally in the team to see what makes sense.