I wrote a doc about using CUBE functions in Excel to query PowerPivot Data and decided to give it to Rob Collie at PowerPivotPro to post as Rob is doing a great job of promoting PowerPivot and I wanted to contribute.
The link is:
http://powerpivotpro.com/2010/06/21/using-excel-cube-functions-with-powerpivot/
I think this is an exciting capability of Excel and PowerPivot and I hope others jump on it.
Dick