An in-memory OLAP cube that can for instance be installed and used in Excel. It allows for fast analysis of huge datasets.
PowerPivot is part of the Microsoft Business Intelligence suite and uses SQL Server in the background, but it is geared towards the data-savvy business oriented person. It allows you to easily load data from different sources, put them in a relational database-like format and create relationships between the tables.
When all data is loaded, an OLAP store is created in the background and you can do real time analysis by selecting and filtering to your heart's content.
Also included is a powerful query language called DAX (Data Analysis eXpressions) which use an Excel style syntax to allow the user to perform complex calculations.
Power-Pivot datasets can also be served as part of SharePoint and Microsoft has even put at least one all-in hardware appliance on the market in collaboration with hardware vendors.
The following links provide useful reference information:
Further interesting PowerPivot articles can be found here:
