One of the interesting use of powerpivot came to my attention when I saw use of powerpivot with Microsoft Codename Dallas. Dallas is still in the alpha version, and seems to be an interesting concept. It can be thought of as a potential new tiny Amazon.com in the market place of service subscription business.
Any business that is providing it's content in the form of service can partner with Microsoft and take advantage of the Microsoft's sales channel. Microsoft would provide these services via Dallas, which users can subscribe by paying for the required subscriptions. Content from these services would be made available in a structured format (like in the form of a dataset or in Excel) to the subscribers.
This content can then by readily analyzed using Powerpivot. This is a very interesting part of cloud computing, and powerpivot comes to its most appropriate use for business intelligence, in my views. Powerpivot of course is a very powerful mechanism to analyze huge data in a way that was not possible just using excel, but that felt much more like an add-on to me instead of real time business intelligence. But now when data from Dallas can be analyzed by joining with other sources of data using powerpivot, this is what I feel is real business intelligence.