For the unofficial Google Reader API, I can get all items for a feed in the Atom format. Are they also available in the JSON format?
Google Reader exposes feed data as JSON at URLs of the form http://www.google.com/reader/api/0/stream/contents/feed/*escaped_feed_url*
, e.g. http://www.google.com/reader/api/0/stream/contents/feed/http%3A//blog.stackoverflow.com/feed/.