The following link provides download and installation instructions for the Data Mining add-ins for Excel and for SQL Server 2012. Note that if you have this version, you can also connect to servers running SQL Server 2008 and SQL Server 2008 R2.
SQL Server 2012 Data Mining Add-ins for Office 2010
Information about system requirements, architecture, and performance
Tips on maximizing compression, and determining which columns are using the most memory
Kasper DeJonge: Using data mining results in a tabular model
How much training data is enough?
PowerPivot deployment whitepaper
Mark Tabladillo presentation of integrating PowerPivot with data mining
PowerPivot team blog