Is anybody out there returning Usenet newsgroup messages as XML? No? Why not? Seems that hierarchially-organized plain text messages with lots of metadata might lend themselves to that sort of presentation.

Try this: Use the Google API to find messages in response to a query, then cache the result and map the returned message IDs to a private NNTP server with a custom front end that transforms the messages into XML. Give it a REST front end. And offer me RSS feeds of messages from newsgroups so I can read them in my microcontent browser headline syndicator. Or in Sherlock 3.0.