Searching and Navigating Code in VS 2010 (VS 2010 and .NET 4.0 Series) - ScottGu's Blog:

VS 2010 introduces a new “View Call Hierarchy” feature that allows you to quickly discover where a particular method or property within your code-base is being called from, and allows you to quickly traverse the call tree graph throughout the code-base (without having to run or debug the solution).

Wish I'd seen that three hours ago.  So much easier than a breakpoint and walkthrough.