Is there anything like IMAP servers for reading RSS/Atom/etc feeds? I’d like to keep track of which posts I’ve read and which I haven’t, and what I’m subscribed to, consistent through a large set of computers. But I also like the ability to use a number of different clients, which is why I don’t want to be tied into a Web-based reader.
Update: a couple more requirements are (1) that I can set priority levels for feeds to sort them, and (2) that it will recognize when I’ve read the same post on a different Planet and mark it as read everywhere. The second requirement should be a function of the client rather than the server.