An RSS channel typically has one writer and multiple readers.  Some bloggign software allows multiple writers per channel, channel sharing is limited to the deployment site.  How can we have shared channels across sites and writers?

First, feed directory services like syndic8.com and weblogs.com must support multiple channel feeds per channel.  To identify channel, we can either use the channel title or add <guid> to <channel>.  With <guid> approach, title coherency is a problem.

Second, some arrangement must be made to make it easy to subscribe to shared channels.  Client-based approach could start with one feed and find other feeds for the channel either directly from a channel directory service or from the feed itself.  In later approach, each feed is responsible for finding other feeds for its channel.  Server-based approch relies on channel directory services like syndica8.com to provide channel feed aggregation service.