WordPress.org

Pretty simple, really. Adds a new type of feed you can subscribe to. Simply add ?feed=json to anywhere you get a normal feed to get it in JSON form (but with a cutdown version of events).

Version 1.1 added support for JSONP. To get a JSONP response instead of a normal JSON structure, simply add jsonp=callbackName to your query, where callbackName is the name of the function to be wrapped with.

To use this with jQuery, you'll want to do something like:

$.getJSON("http://example.com/feed/?feed=json&jsonp=?",
       function(data){
               console.debug(data[0].title);   // print title of first item to firebug console
       });
});

(thanks to Dan "Tack" Trudell)