One of the biggest shops here says May 3rd. (Norway)
I really hope none of this is the case. But there are sh!tloads of journalists that will get it first, you know, the Olympics and all. But I am optimistic, I've been through this before with both the mk3 and mk4, and I only need one, and with a little patience and some lobbying, I usually end up with a very early one. Not that hard, but just sign up for a waiting list is not going to get you one, at least not early.
On a sidenot, I tried one today, and my god, however long we have to wait, it is sooo worth it. And do not worry about the buffer, I kept the button down for over 4 seconds and it didn't slow down at all, and the memorycard inside : Kingston 8gb 133x speed

The lowlight AF is beyond anything, and the sheer response of the whole camera is mindblowing!! It makes the mk4 look like an expensive toy, old and sluggish. The 1d X VF is the biggest and best I've seen ever. But, again, the response of AF and shutter is just out of this world. You can so very much feel how much faster it locks AF and that it is NO lag before tracking.
It has the new "Zoom in in play mode" like the Mystery Camera. Push Play and then the magnifyer (placed right next to it) and boom , 100% cut. The buttons have all been reworked and give great feel, even with gloves now, the AF-ON button is leaps better. The new joystick makes the camera feel very simmiliar both in portrait and landscape oientation.
The ultimate camera.