I'm also following all of this on xda and one person's talk with customer service indicated that if you haven't got the back-order email yet, then you're probably in the clear.
Another person said they ordered around 8:35 pst and they got the email so it seems random- order time will make no difference. The people that ordered late by f5ing might all get axed though.
It stinks. Google obviously didn't realize the initial demand they would have. I would have thought they would have timed the next wave sooner than 3 weeks and went from there, but who knows.
Given the type of following Nexus devices get, they should have realized that this device would likely have an early surge from enthusiasts before tappering quicker than normal. Now they might push to manufacturer tons of devices only to get hit with a drought in demand after all initial orders are filled.