PowerPivot is a cool tool, and if you are an intern or IT Administrator, you may be hearing a little about it.
What is PowerPivot for Excel (see: http://msdn.microsoft.com/en-us/library/ee210692.aspx)
PowerPivot for Excel supports self-service business intelligence in the following ways.
Current row-and-column limitations in Excel are removed so that you can import much more data.
A data relationship layer lets you integrate data from different sources and work with all of the data holistically. You can enter data, copy data from other worksheets, or import data from corporate databases. You can build relationships among the data to analyze it as if it all originated from a single source.
Create portable, reusable data. Data stays inside the workbook. You do not need manage external data connections. If you publish, move, copy, or share a workbook, all the data goes with it.
PowerPivot data is fully and immediately available to the rest of the workbook. You can switch between Excel and PowerPivot windows to work on the data and its presentation in PivotTables or charts in an interactive fashion. Working on data or on its presentation are not separate tasks. You work on both together in the same Excel environment.
Here are some links:
Securing PowerPivot (very important):
Sharepoint and PowerPivot:
Power Pivot Client Server Architecture Posters