Next up pubsub with a demo - I subscribe to a bunch of PubSub searches, so this should be of interest. A year ago - they were tracking 100,000 blogs. It's leaped to 10 million now, and it's still growing.

How do you monitor the content you care about? There's the "subscribe to it all" Scoble approach (1300 blogs), and there's the watch/search based pubsub approach. Most of us do a little of both - I read specific people, and I search for specific keywords. PubSub is leveraging the publish/subscribe nature of the blogosphere. So in timeline terms, we had email in the 80s, browsers in the 90s, and blogs/aggregators now.

To compare, he's pointing out that searching (i.e., Google, MSN, etc) you have retrospective search. You get whatever the crawler found last time it looked. What you have with PubSub is a prospective engine, where they get new information sent to them. That allows them (within the publish/subscribe universe) to have much more current information. Essentially, they store the queries, not the results - when a query is made, they match and discard. This means that you don't want to use PubSub for archival information - you want to use it for current information.

When do you need something like this? Brand commentary searches, "ego searches", etc. When you want to find new mentions of a specific piece of information. It's a way to track whenever something is mentioned - for instance, whenever a positive/negative mention is made of your brand/service.