Sigma 70-200 2.8 OS available for pre-order

Sigma's 70-200 2.8 OS, announced February of this year, is now available for pre-order from Amazon for Canon, Nikon, Pentax, Sigma, and Sony mounts.  I think this is the first and so far only third-party 70-200 2.8 lens with image stabilization.  As expected, it costs less than the equivalent lenses from Canon and Nikon, but it costs about twice as much as its non-stabilized predecessor.