The Nikkor 20mm f/1.8G ED lens is currently in stock at B&H (with free expedited shipping). More information on the latest Nikon lens can be found here.
Update: Nikon D750 now in stock at Amazon as a #1 best seller in the DSLR category (available from Amazon, not by third party):
Nikon 20mm f/1.8G ED lens unboxing video: