Definitely no kensington lock.
And as I suspect once the price to manufacture retina displays goes down, eventually Apple will ax the non-retina MBPs.
Apple prefers to have a simplified, focused product line.
That being said, we can expect that in a few years, no apple products, other than desktops (whoop de do) will have kensington locks.
Apple apparently lives in some magical land where theft doesn't exist.
This is the only hope:
http://www.maclocks.com/index.php/macbook-air-lock.html
But something for the new MBP obviously.
However, I am skeptical as to a new locking case for the retina MBP being possible.
The new unibody design is very particular about having unobstructed air flow into those new slots.
Sure a new case would mirror those air flow slots, but wouldn't a non-metal case hurt heat dissipation?
10 bucks says that apple did not factor in affixing a non-metal case onto the retina MBP when designing the thing. So people who buy a case might see slowdown as the processor throttles to avoid overheating.