Microsoft has been working in overdrive with the release of PerformancePoint 2007, now coming close to a year in age, and there has been a large output of material from teams within the MS castle. I came across this gem recently after having heard some rumors of its existence. It was actually published in 2006, a year before PerformancePoint, yet in the wake of SQL 2005, which completely changed the game for Microsoft in the enterprise ETL space.
What made it hard to find (for me at least) is that it was posted in CodePlex, which I normally attribute custom projects and development to, not design and architecture guides. Here is the link:
Srinath Vasireddy of Microsoft was the program manager for this design guide; his personal blog can be found at: http://blogs.msdn.com/srinathv/default.aspx