RSS based ranking or maybe a new protocol is needed?

RSS is a protocol for transmitting changes within blogs that has been widely adopted and provides a solution for a big problem people had in tracking changes in content effectively. RSS is doing a perfect job in providing updates to content based on time of change but still lacks support for providing other criteria for ordering changes.

At first RSS has been used solely for providing list of recent changes whether for blogs or other content management systems such as wikis. Now it seems that RSS is used more broadly to provide access to recent list of data items that are different one from another not only by time of change but also by order of importance for example.

If we take Techmeme for example, they provide actually and ordered list of stories (blog posts or news) where the order is based on importance. Consuming Techmeme via RSS does not unveil the full picture of importance within Techmeme since date of publication is the only criteria RSS readers know to consider during display. Together with Techmeme we can put any search engine results delivered via RSS, bids for an auction and more..

Does anyone have an idea for a protocol or maybe some trick to reuse RSS while maintaining true order of items during presentation?