PowerPivot and PowerPivot for SharePoint, try it now for free (RTM Trial links) !
With the official release of SharePoint 2010 to RTM Microsoft has released both products needed to run PowerPivot client and Server. So we are finally good to go 
The great thing is that you can try all products for free.
- Download SQL Server 2008 R2 here. (180 days)
- Download SharePoint 2010 here. (180 days)
- Office 2010 here (60 days trial)
- Get the PowerPivot client here
Check out my blog post Getting started with PowerPivot
