Collaborative 'summary of useful points' for Reddit/Hacker News kinds of posts

Sites like Reddit and Hacker news are made up of posts, and each post is about some topic and contains a discussion thread about that topic.

The idea I want to talk about would probably be most suited to certain types of posts, not all posts. It'd be suited to posts like those about news stories, where the discussion threads usually contain a lot of interesting information that fleshes out the picture of the story.

That interesting information tends to be lost amongst a lot of "noise". It'd be quite useful to have a condensed summary of all the useful information dispersed throughout the thread. I could imagine the post having two tabs. A 'thread' tab (shown by default) and a 'summary of useful points' tab.

Is there a way we can incentivise the collaborative work of constructing this "summary of useful points"? And have a sufficiently simple design?

The following are two ideas for how it could be done. These may not be suitable, but they're at least starting points for thinking about the problem.

The first idea is to allow users to add bullet points, where each one contains a 'useful point' summary, and for these to be voted on, where their number of votes controls whether they're shown as part of the summary of useful points.

Notes

• limit on the size of the bullet points. Perhaps 280 characters, like tweets.
• if a bullet point has had more than, say, 20 votes, and is in the negative, then it will be hidden (though there's a link to view the hidden items).
• let the users link a bullet point to the bits of text in the discussion thread that originally made the point. The UI details of this are beyond the scope of this post.

The other idea is that the summary of useful points is updated via a 30 minute cycle that involves a number of phases:

1. 10 minute phase where anyone can suggest changes to the current summary. Each is limited to 280 characters. People can vote on these suggestions.
2. 10 minute phase where anyone can write a new summary. They can use the pool of suggestions to help them decide what changes they want to make to the current summary.
3. 10 minute phase where the new summaries are anonymously shown for voting. When viewing a new summary, users can see a diff of it compared to the current summary.
4. The top voted summary (if it passes a critical threshold of votes) becomes the new summary, and the cycle repeats.

Notes

• users can have the thread highlight new comments added since last time the summary was updated. There could be buttons to navigate to next/prev new comment. 
• users can view history of changes to the summary.
• the summary tab would show a representation of the update cycle and indicate where it currently is in the cycle. 

Could there be other possibilities? Could there be something that doesn't involve any threaded discussion at all?

Perhaps you could have a system that cycles between two phases. One is where there's a discussion thread. The next is where that content is condensed into a summary. Then this is summary is a seed for further discussion, and then the current summary plus the new discussion is condensed to form the new summary, and so on. At the end of each cycle only the summary is kept (the comments are effectively discarded -- though perhaps a read-only view of them can be accessed).

.

Related

• I believe Stack Overflow originally wanted to have a feature a bit like this, but that doesn't seem to have panned out. Would be worth investigating.
• Are there any other systems or designs doing something similar to these ideas?
• Back in 2005 I wrote Slashdot Article Summaries?, which was a more basic take on the ideas outlined in the present post.