This is the end result of the report I created in under 10 minutes during the BI Power Hour at TechEd 2006. It uses a matrix report and takes advantage of the parent-child nature of data mining content to render the hierarchy.
The .rdl file for this report is attached. All you have to do is change the connection and query string to point to your server and tree as appropriate.
<added bitmap 'blue' 8/1/2006 - jamiemac >