We're still waiting for cross-platform play between PlayStation 4 and Xbox One users. But in the VR world we now know that cross-platform play will be available for certain titles, including Eve: Valkyrie, which will be updated in the future to allow players using Oculus Rift, HTC Vive and Playstation VR to join up with users regardless of which VR headset they're using.
The Oculus Rift and HTC Vive are available now, but Playstation VR doesn't ship till this fall and is expected to quickly gain the largest user base thanks to compatibility with every PlayStation 4 console.