Even though there is still very little information available on this lens, I believe I just read in a web forum what is the definitive meaning of it. This lens, and the new family to come with it, is the answer to the Leica S system.
There are a few tests published online that compare the D800 to the S2 (Ming Thein's is excellent, and free to view) and every one of them ends with "but the D800 doesn't have as good lenses". This lens puts an end to that.
I can't wait to get more information. More than a vague comment.
Also: I hope this isn't the industrial design they're going with.