• This is a pretty good book with all the basics.

    http://www.marktab.net/datamining/index.php/2010/11/05/data-mining-for-business-intelligence-book-review/

    Also, for SQL specific Data Mining for SQL Server 2005 (although I believe that the 2008 edition is out). It covers SSAS as well as the specific algprithms available in SSAS.