I've been heavily involved in PerformancePoint implementations since the beginning of that product's lifecycle...our company has done many deployments for clients. It's a great dashboarding technology, and I'm continually amazed how quickly we can put together compelling solutions with it. The efficiency and elegance of the underlying design strikes a great balance between power and simplicity of use.
Recently Microsoft folded this product into SharePoint as part of the Enterprise CAL. The net effect for eCal customers is a "free" enterprise-class BI platform; and for customers that would have invested in the BI platform anyway--all the benefits of eCal, including Business Data Catalog, Excel Services and so on.
Here's a Silverlight video going into some additional detail of the benefits of combining PerformancePoint's monitoring & analytics with SharePoint: