No, it's not. Goran's on the wind-up again. I think he's bored this week.
The only diffuser rumours I've heard from anywhere were about the possibility of using the rear crash structure to help link to the rear wing (I assume the crash structure position has changed with the rear wing changes but I haven't looked at the regs).
For trick stuff I have heard rumours that the brake duct changes may let you do funky things with them when the wheels are steered - because they're only defined in a static position (I assume mount them to the suspension members rather than the upright? If someone's got a model of the bounding boxes made up it might be worth a look? Or someone has access to the regs and the tech directives?), but I'd imagine that would be hell for airflow simulation. Mclaren have had enough fun with that already
That was on another forum though, not from a factory.