PowerPivot and BI architecture

PowerPivot is the new Excel 2010 add in and a server application in Sharepoint 2010. What will PowerPivot change in the existing BI architecture or in the everyday life of existing BI-solutions built on the MS-BI platform?

 Amir Netz suggested the anology of the freedom of the Blogs compared to the newpapers and tv-channels views of the world for the role of PowerPivot in a BI solution, in a discussion on Linked In. I guess that he means that the end users will be able to build their own analytical subspaces of their organizations information stores. He also agreed on my assumption that PowerPivot will not replace the centralized data warehouse vision.  My personal experience from working in a fairly large company with a centralized data warehouse is also that changes takes far to long time to implement.  The time horizon from a requirement to an implementation of that requirement can take 6-8 months. At the same time the requirement for reporting will change much faster that that and put a lot of pressure on the end users