<p>Recently I have been doing more complicated math in OpenSCAD and I have run into something that I find strange. Take a simple math expression: <code>2 / 2 / 2</code>. By any programming language this will equal 0.5 (1/2), and OpenSCAD agrees. Something like this: <code>2 / -2 / 2</code> should also be -0.5 for the same reason. However, OpenSCAD thinks this is -2. That is <code>echo(2 / -2 / 2);</code> gives <code>ECHO: -2</code>. My calculator, other programming languages (and myself) all say its -0.5.</p>

<p>Is this a quirk of OpenSCAD, or am I missing something obvious?</p>

I suspect the behavior you are seeing is an undocumented feature (aka, bug) of OpenSCAD. I've found in the latest stable release that if the - is placed on either end, the result is -0.5, but in the middle, my results are the same as yours. Surrounding the -2 with parentheses results in a correct answer, however.
It appears that the parentheses turns a mathematical operation into a signed integer. It follows that the operations without the parentheses is right to left:
2/2 = 1, negative 1 with the minus, 2/-1 = -2