It is manufactured and engraved in the same place - a sweatshop called Foxconn. Typically, stuff comes to Apple warehouse and then gets shipped, but this time, it looks like Foxconn is doing the entire thing. Apple has many more channels to supply this time (Best Buy, Fry's, Walmart, Target,...) unlike earlier launches and so they must have done this to squeeze out some more from the supply chain - it does make it more efficient as well. But, Apple looses and local control on the process of inventory as you see that it takes 2 days at least to make changes to inventory in USA as nothing is stocked here as yet for iPad-2. My wife's Macbook Air also came the same way as her config was a non-standard one and it had to be built to order in Shanghai and then shipped directly from there - even then Fedex delivered 4 days ahead of schedule (total time 2 days).
If you think Apple has screwed up this launch for this order booking on launch thru so many channels, you have to ask which company can do better. I work in semiconductor industry and am not in Operations, but it is an extremely difficult job.
Bah! There, I am shilling for Apple. Never thought I would do that. 🙂
PS: One of my iPad is in "Prepared for Shipment" stage for over 24hrs now and the other is in Shenzhen waiting for delivery on 23rd. And I placed my orders @ 12:40AM and 12:42AM PDT on 11th.