HDInsight: Microsoft's move to gain share in Big Data Market after trying to create its own big data management platform, aka dryad, LINQ to HPC, Microsoft has decided to stop researching on it and explore the Apache open source big data platform HADOOP. It's a well established and a widely used big data platform for performing computation over big data.
With partnership of Hortonworks, Microsoft has successfully delivered HDInsight: Hadoop Eco-System for Windows Server and Windows Azure. Also empowered Microsoft's products SQL Server, Excel, C#, LINQ to work with Hadoop Eco-System.
Take a look of its high-level architecture.