Instapaper has added a new feature on their Download option. As well as downloading as a Kindle .mobi or an .ePub ebook file of the latest 10 articles, you can now also get an RSS feed for your latest 25 unread articles. The articles appear in the order you saved them into Instapaper, and each Web link goes to the newspaper/magazine original article URL rather than to your Instapaper copy. At present I’m uncertain if the 25 links are “fixed”, or if the feed is a rolling dynamic one that will update as I add more articles to Instapaper.
Update: yes, it’s rolling RSS, updating as new articles are saved.