You've possibly seen a few murmurings on the internet along the lines of "ZOMG the PlayStation VR works with the Xbox One! Whaaaaaaaat?!" And yes, it's true. Sort of. It's also not really anything to get too excited about because you're not suddenly going to have lots of Xbox One super happy VR fun time.
It takes advantage of the PlayStation VR's Cinematic Mode, which is little more than a giant, cinema style screen before your eyes. Hence the name.
The Xbox One can use this by virtue of the 'wonders' of HDMI. By attaching an Xbox One and not a PS4 to the processor unit, you'll see a large projection of the Xbox One's output. And sure, you can play games this way, but there's no benefit to doing so over playing on your TV or monitor.
I played a mission of Call of Duty on my own PlayStation VR in Cinematic Mode and it was generally a worse experience. My eyes had more 'screen' to cover and the detail wasn't nearly as sharp. And while you can make mild adjustments to the size of the display on the PlayStation VR when it's hooked up to a PS4, you don't have any of those luxuries in this unholy matrimony.
All PlayStation VR adjustments are made on the console, so you're stuck with what you have.
If you have both an Xbox One and a PlayStation VR, then sure, it's a neat trick. But it's also largely a useless one and you gain basically nothing other than blocking out the world around you to look at the same, 2D interface and games. You could probably plug in an Xbox 360 with the right cable, even your PC. I could do my writing with the PlayStation VR headset on in theory. But I don't want to.
If you want to find out more about what PlayStation VR can really do, head on over to our buddies at VRHeads where you'll find a wealth of great content!