According to CVG, Sony originally planned to reveal a PlayStation branded virtual reality headset at Gamescom, but plans to reveal it fell through at the last minute. Apparently, growing support for the Oculus Rift has complicated some of their plans for the device, as well:
It originally intended to reveal the Sony headset at Gamescom but plans fell through at the eleventh hour. The company is currently weighing up whether the PS4 device should be pitched as a key differentiator for the console or a non-essential add-on.
The matter has been slightly complicated, but not derailed, by the growing industry support for Oculus Rift. Sony's device will be a categorical rival to Oculus, and for months there have been rumours suggesting the two companies are seeking a partnership.
Some anonymous game developers have told CVG that the device indeed exists and is being used to simulate things such as a cockpit view for Driveclub. The device itself will apparently be available separately to keep the PS4 baseline price low.
I'd say that this would be a pretty big deal if it's true. Competition for the Oculus Rift could only be a good thing and it'd mean that Sony would support virtual reality in their games to a certain extent.
Eurogamer has also supported this rumor.
According to gamesindustry, Sony's VR device, said to be more accurate than the Oculus Rift, will not be shown at TGS but is expected to be released in fall 2014.