Hashtags on Twitter are AWESOME; they can organize tweets around a particular topic. However, the value of a hashtag lies in the "here and now". If I search for #sllconf during or right after the event, I get tons of sweet content. However, searching for #sxsw in June gives you a wasteland of useless tweets... all the cool stuff was from March, when the event was happening.
Enter Keep Stream: A collection of tweets that can be "kept together" to tell a story. I imagine this will be used for real-life events, news stories, and twitter conversations. Think of it as a way to preserve and organize the best of the real-time web.
Check out the collection. I'm curious what y'all think of it and Jim's product.