Sony's Andrew House took to the stage at PlayStation Meeting and there he confirmed the PS4 Slim. After revealing that this generation of consoles had sold more than 40 million units, House went on to say that the Slim would be the standard PS4 moving forward. The slimline console is coming out on September 15th in most markets, and it's going to cost $299 / £259. There will also be a 1 TB version, but we don't know how much it will cost yet. We've contacted Sony for further details.
It's also worth noting that it will support HDR out of the box, same as the original PS4 (via update) and PS4 Pro upon release.