Rss-Data and RSS 2.0 Extensibility

Note: this entry has moved.

I believe extensions through namespaces is a great addition to RSS 2.0, but one that was also possible with the W3C RSS 1.0... I imagine an extensible plug-in architecture that would load plugins from URL-retrievable namespaces (that would be a convention, of course, such as "http://danielcazzulino.com.ar/rss/metadata"), and that would participate in the item's rendering process, either server-side or client-side in a news aggregator. The returned plug-in would have to conform to some interface and would be readily downloaded and executed (CAS approval assumed...).
For the server-side, I even imagine an Accept HTTP header that would tell it whether the client requesting the RSS feed supports a certain feature, for example, Accept: x-include. If such a header was not present, the server could pre-accumulate the XInclude-d fragments from other sources.