I’ve just looked into the communications again (have written a small tool for low-level daap browsing), I’ve seen you’ve already added custom content-codes, e.g. org.mt-daapd.addplaylist (btw, will you rename those to org.fireflymediaserver…. or keep them?).
So my suggestion would probably be to extend the /server-info page with a new org.mt-daapd.statusinfo container that would contain the information required.
Since that would need the gnome panel app to be able to parse daap output (which is really not that difficult if you don’t need that ugly Apple-changed MD5 algo), others would probably prefer some kind of XML (urks 😉 ).