Yeah, that BOL article is misleading, I would argue that PowerPivot is completely unrelated to SQL Server 2008 R2, it depends on Excel 2010 and is a separate web download into that tool, you can use that without using SQL Server at all. Was pretty sure the Multiserver admin was already there too, but that's not my strong suit.
I agree with you, Power Pivot is a an addon to Excel 2010 and is built on VertiPac, but in Denali the VertiPac will be implemented in SSAS and it will be implemented in the project Crescent.
atabase Developer 2008
MCTS: SQL Server 2008, Implementation and Maintenance
MCSE: Data Platform