The production capacity of the Thailand factories is higher and with additional lines so production can be changed with demand. The normal consumer products are usually available soon after announcement but the higher end bodies and lenses that are made in Japan are built in facilities with less flexibility. The initial demand for the D800 was higher than any pro level camera before and they never intended to build more then 30,000 a month. First day orders were probably 100,000. Production has caught up to sales apparently since D4, D800 and D800e were available off the shelf 2 weeks ago when visiting Poland and here in at local mall shops have them for immediate delivery.
The D600 will likely be an even bigger hit, particularly after the previews of the Canon 6d shows that the D600 has no competition. Stan St Petersburg Russia