After seeing a demo of PowerPivot, I was reminded once again that no matter what "BI-for-the-masses" tool selected, business users won't benefit that much w/o a strong understanding of their own data as well as basic data relationships (cardinality, granularity, etc.). The ability to "mash-up" data from disparate sources is challenging enough for IT people with expertise. To expect that the garden variety end-user will easily be able to do this is a bit optimistic.