Microsoft BI TechCenters: Learning and Resources
Apart from subscribing to the blogs and reading the books in the Sites and Blogs and Books sections of this blog you can also visit the following TechCenters on TechNet and MSDN:
SSAS – Multidimensional Data
SSAS – Data Mining
PowerPivot for Excel
You can find a good collection of whitepapers, articles and links to various resources.