Yeah, I'm not sure whether to go for ultra-perl-like code vomit full of regexes and operator hacks, or to go for tight but clear code. It seems the top-rated solutions are usually the most ingenious and use the most language hacks. It'd be great if there were different ways of giving ratings - perhaps one for most maintainable and one for most inventive :)

I think it's actually a writing style choice, there's not really a set rule about the Oxford Comma :)
http://en.wikipedia.org/wiki/Serial_comma

I like the chunk idea :) It'll change 'numbers' for the caller, but it's super clean to read.

Yeah, I have no idea what question is being asked, or why there are two test fixtures being talked about (your own and the test's.) What is the goal for this kata?