Jekyll is a giant...
think of the best word you can to finish that thought

One would think that Jekyll would be easy to use - truth be told, it probably is easy to use. There's YAML and there's Liquid. Both are fairly straight forward, not terribly robust, but they are concepts which are eas(ier) to grasp than most.
I even like Jekyll's official page - their documentation doesn't suck either.
All that said, every so often, I am just damned capable of breaking something.

The problem?

In a nutshell, the _site folder was updating exactly what was written in any file in the root folder. That means, that instead of rendering (or, piecing together) all the little bits and bops like Jekyll is supposed to do, Jekyll was directly adding YAML as text.
That not make sense? Not enough detail for all you Stack-Over-Flow guys n' gals? Lemme break it down further.
...

The solution

I needed to flush the _site folder. That's the best explanation I can come up with. I couldn't find anything of the sort on the interwebs - that might be my own short-coming, and I nearly wrote a SOF Question to figure this out...I just can't be bothered to prove myself to you bastards. No offense. :}
$ jekyll clean does the trick, i.e. it erases the build within your _site.
Follow that up with: $ jekyll build and you're good to go.