What looks to be the biggest and best new feature in SQL Server 2014 is called the “In-memory OLTP Engine”, code-name: Hekaton. In short, Hekaton is a SQL Server In-memory OLTP Engine. Hekaton provides in-memory OLTP capabilities built into core SQL Server database to significantly improve the performance of your database application. Hekaton is installed with the SQL Server 2014 Engine without requiring any additional actions and allows in-memory performance benefits without rewriting your database application. You can also increase performance of existing SQL Server applications without having to refresh your hardware. Hekaton is easy to deploy and allows you to access the other rich features in SQL Server, while taking advantage of in-memory performance.
This complements the existing in-memory data-warehousing and business-intelligence (BI) capabilities already in SQL Server via xVelocity. Hekaton could benefit DW/BI solutions in two ways that I see: 1) By speeding up the time it takes to pull data from a source system that is in-memory into the data warehouse, and 2) Instead of persisting staging data in tables on disk, you can store them in memory.
Here is the description from the Microsoft site:
Hekaton in-memory OLTP: In-memory database technology that will provide breakthrough performance gains 10 times for existing apps and up to 50 times for new applications optimized for in-memory performance with no additional hardware required. There will be a diagnostic tool that will suggest which databases and tables are the best candidates to run in-memory. The “Hekaton” codename will fade and it will be referred to as the SQL Server In-Memory OLTP Engine.