Well, how many people saw that coming? A 4K Hero!
Admittedly it's only 12 frames per second (in "Cine" mode and in Pal regions; 15 fps otherwise) - a bit low, perhaps, but surely signalling their intention to be at the forefront in ultra HD sports camera technology. 2.7k in Cine mode at 24p looks usable in the right context, and 720p at 120 fps is a very good compromise between resolution and high frame rate for smooth slow motion.
But what really matters is this. Everything about the Hero 3 is twice the capability of its predecessor. Twice the resolution, and twice the framerate - not to mention twice the low-light performance. All of which adds to the evidence that camera technology is improving exponentially.
We'll be testing this as soon as we can get one, but for now, if anyone had any doubts that 4K is here - or, for most people - just around the corner - then they haven't been paying attention.