Hmmm....I'm not seeing what the driving force behind this choice of FL was for Nikon. They have lots of other gaps in their line-up but macro lenses seemed to be well covered with their newer lineup of 60, 85 and 105.
I'll be taking a pass on this one as I own the 60 2.8G and 35 1.8 (and didn't like the FL of the 50mm so I sold my 50 1.8). The knock on the 60 2.8 is that for many it doesn't give enough working distance - that knock just got a lot louder for the 40 2.8.
Looks like Nikon Rumors missed the boat on this one!