I am in the process of developing an add-in package for Visual Studio 2010. Previously I was having issues when running the debugger against the package it wasn't finding the included assemblies. I had looked at writing a custom assembly resolver or adding a build step to copy the assemblies to a folder that the VS debugger looks at.
Then I came across the answer on this post mentioning the ProvideBindingPath attribute and suddenly everything started working perfectly.
Thank you Aaron Marten!