Power to the Pivot

I've been spending a good bit of time with PowerPivot in recent months, primarily as part of a proof of concept exercise for a client. Like many others I have to say I started looking at it with a high degree of scepticism. Surely I thought, this thing goes against all of the principles we've been trying to drum into users, particularly the importance of building a well designed Unified Dimensional Model with calculated members in our Analysis Service cube - then we get that "one version of the truth" that we're all after when we build a Business Intelligence solution. PowerPivot on the other hand is a free add-in for Microsoft Excel 2010 which lets you load very large amounts of data into memory work and with it in a new desktop version of Analysis Services called VertiPaq. So you build your models, including all the calculations, inside of Excel.