After some discussion on the Test::Harness developers list, I proposed we allow something like this (ignore the namespace):
You get the idea.
Basically, it would be problematic with how streams work (you don't read just "one" line of XML), but it would be nice to be able to throw any test output format at TAP::Harness and have it know how to read it. Combine that with App::Prove::History to store test results over time and companies might find gaining ISO9000 compliance for the QA easier.
In fact, with more robust output formatting control, TAP::Harness could become a de facto test harness for many different languages.
And before you mock me about ISO9000 compliance, the reality is that many of us work in corporate environments and we have to do the best we can with the constraints imposed upon us.