Yes, it's been doing the rounds for a week on Canon Rumours web site - interesting response to the 1DX.
The only real bonus seems to be the QXD card that means you can shoot 100 full RAW images without overloading the buffer.
I'm gonna agree with Jonathan here, in as much as i don't see many Nikon Pros jumping to upgrade, though i bet those attending the Olympics will all be sporting them, as will those at Euro 2012.
The Canon 1DX is much more of a leap for Canon people, but i can't really see either body forcing the big brand jump that the 1D3 caused with its failed AF just as Nikon released the D3 that seemed to work out of the box. So, roll on D800 and 5D3 announcements