latest and greatest denali bits.

http://www.microsoft.com/betaexperience/pd/SQLDCTP3CTA/enus/default.aspx and you will need this too

Microsoft® SQL Server® Code-Named 'Denali' PowerPivot for Microsoft® Excel Community Technology Preview 3 (CTP 3)

http://www.microsoft.com/downloads/details.aspx?FamilyId=80edc21c-643e-4e1b-a4c9-7f51f24b6d98