Are you seeing it listed on Acusport? It looks like a new item, probably a 7.62mm version of the Saker? Apparently titanium, and rated for 300WM.
RSR has it listed also. It looks like the rear mount will be interchangeable, and it probably doesn't come with one. They have threaded mounts listed also in 3-4 thread patterns.
Edit: Now I'm not sure if the rear mount is interchangeable or not. The mounts that RSR has listed, would retail around $80, so they're probably just the flash hider mounts only. I don't see a MAAD-type part number listed that would indicate they have an interchangeable mount body. There are no pics or extended description of anything, so it's hard to tell what's what just based off the price and item name.
Hopefully, Silencerco will be announcing this before the end of the year, and not wait until SHOT 2014 to bring them out.