Rick Bayless carnitas
I have to say I don't remember ever seeing any Rick Bayless carnitas recipe with cinnamon in a braising liquid; carnitas are usually dry marinated first and then cooked slowly in lard, although I have seen recipes where the shoulder or butt is braised in a well flavored stock. I googled around but came up with nothing online. Why don't you just take a recipe you like and play with it?
Here's his basic carnitas instructions:
Here are two older chow threads I just read through; no mention of cinnamon anywhere, but some interesting recipes, ingredients and discussions of technique nevertheless:
Hope you find what you're looking for!