There are definitely a few streams that are very time-dependent and service way more utility near the event, rather than after the fact. Some recent examples, s

There are definitely a few streams that are very time-dependent and service way more utility near the event, rather than after the fact. Some recent examples, searching for "caltrain" after it was stopped a few weeks ago. Searching for "280 flooded" during a rain storm. Searching for "comcast near:SF" to see if anyone else was having connection problems at the moment. We're not used to having down-to-the-second real time search yet, so it's harder to come up with use cases until we really become comfortable with these new systems. Most use cases we do see, like Trending Topics on Twitter, are discovery queries that will eventually be covered by Google's spidering, but there are whole categories worth of search cases in the long tail that won't be covered by just discovery.