I am writing an RSS feed (for fun) and was looking at the spec here.
RSS is a dialect of XML. All RSS files must conform to the XML 1.0 specification,
Well, if you are developing some javascript app you might want to get any RSS feeds as JSON to overcome cross-domain querying issue. There is a reliable Google provided solution that converts about any RSS to JSON. For jQuery lover's there is a universal RSS to JSON converter plugin.
Example:
$.jGFeed('http://twitter.com/statuses/user_timeline/26767000.rss',
function(feeds){
// feeds is a javascript object with RSS content
}, 10);