You are probably asking what is StreamInsight. Well, it is the platform for performing Complex Event Processing (CEP) from Microsoft. Actually to quote exactly what it is - it is a "platform for the continuous and incremental processing of unending sequences of events (event streams) from multiple sources with near-zero latency".
There has been a need to deal with processing at near zero latency for some time. Many times existing products can perform at low latency and that has been acceptable, however, there are a number of situations where low latency wasn't sufficient. That is where Complex Event Processing comes in.
According to Wikipedia CEP is defined as: primarily an event processing concept that deals with the task of processing multiple events with the goal of identifying the meaningful events within the event cloud. CEP employs techniques such as detection of complex patterns of many events, event correlation and abstraction, event hierarchies, and relationships between events such as causality, membership, and timing, and event-driven processes. CEP is to discover information contained in the events happening across all the layers in an organization and then analyze its impact from the macro level as "complex event" and then take subsequent action plan in real time.
Some of the scenarios that call for CEP are:
Manufacturing: Sensors on the plant floor capturing data through device controllers and aggregating data consisting of tens of thousands of events per second with requirements to act on patterns detected to ensure product quality
Web analytics: Instrument server to capture click-stream data and determine online customer behavior
Financial services: Listening to data feeds like news or stocks. Use that data to run queries looking for patterns that find opportunities to buy or sell stock
Some of the features of StreamInsight listed on the download site are:
You can start working with the CTP by downloading it at: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=a3faa562-b6dc-4702-90c6-bf8e08df3b8b