It's just being delayed.Although it seems that it should have been released already 10 times,And 10 times rumored to be delayed...The lens that everyone wants but never appears.(Curious...the concept sounds familiar recently)
But the Bruce attached pic does look better than I would have expected in the corners,It's the first thing I saw (the corners) cause in the center they all will perform. The only thingIs that there are some CA everywhere. There is some hdr processing involded.And as both wide angles and hdr exhacerbate CA, it's expected.
and Nikon is not even capable of producing a 50mm 1.4 without IS that is in the same catagory as the Sigma - a shame!(but then they apparantly want to let it cost no more than 350€)