Ben takes the "throw as an exception dispatcher" idiom to its logical conclusion by presenting a pluggable exception handler.
As Ben says "I'm not sure how many situations something like this would be useful in, but it fit the testing problem well and was fun to write anyway". It's not the kind of code you need every day, but it's useful stuff if you're working on a test framework, or if you're interested in how you can use the "throw as an exception dispatcher" idiom.