UPDATE: Valve reduced the 'Steam Frame Verified' tag VR FPS requirement from 90FPS to 72FPS, and import logs show pallets of the headset arriving at the company's US warehouses already.
UploadVR
Alongside launching the 'Steam Frame Verified' label, Valve confirmed that the headset is shipping "this summer":
UploadVR
Alongside launching the 'Steam Frame Verified' label, Valve confirmed that the headset is shipping "this summer".