No: tptacek did not bother paying attention to the context; as far as I know "uint8_t * data, * buffer, ;" (spaces added after * to avoid italics) would never be valid.
How is that the context? In the sense of the intersection between Javascript and JSON, trailing commas have pretty much always worked in C, which is something all of us who write code that generates C rely on, like a lot.
edit: I was wrong: http://www.lysator.liu.se/c/ANSI-C-grammar-y.html#initialize...