This is a very clever idea. Building upon the same types of features you might find in a modern email client, like folders and tags, you would get quite a useful set of tools for organizing incoming items. Something arrives in your inbox from streams you subscribe to, and you file it based on what you are going to do with it. Such as whether it's a todo, a task, a calendar event, an article to read later, a reference item to refer to, whatever.
Once you're done with it, you could then store them (notebooks?) for later, possibly associated using links to other items. Your workflow would go from the stream (incoming) to your inbox (active) to your notebook archive (completed/logged archive).
Once you're done with it, you could then store them (notebooks?) for later, possibly associated using links to other items. Your workflow would go from the stream (incoming) to your inbox (active) to your notebook archive (completed/logged archive).