Honestly i'm really surprised MS+Nokia haven't got the app there yet. Personally could care less for Instagram, but i'm sure those two companies know it's important.
Nokia single-handedly got Rovio to make Angry Birds and one special game (Bounce Evolution) for N900 before even Android got the game. Device that probably sold around 100 000 back in 2009.
I'm just thinking that MS and Nokia would probably happily do the software or pay for the work.