I've been toying with the idea of implementing an RSS theme for CAREO, mostly as a way to prove that theming really does work, and that the interface really CAN be anything (including a machine-readable XML feed).
Stephen Downes was talking about RSS and Learning Objects at the IMS Technical Meetings (from what I hear), and Brian Lamb is talking about it too.
Might have to whip up an RSS theme that will expose an XML feed for stuff like Top Objects, Newest Objects, or perhaps a search query? They'd have to be run as the Guest user, since I'm not about to do authentication from URL parameters (something about security or some such thing...)
I'll give it a shot, and post some URLs when they're ready... Looking forward to subscribing to these things in NetNewsWire!