Not sure if this helps or just adds fuel to the speculation, but this sort of thing happened with the iPhone 4s. I got a notice that it was being "held" for delivery when they would appear in the stores, and I ended up getting mine the day before.
Like others here, I've got an email from Apple saying it's currently in Nashville (I'm in Florida) being held for delivery on the 16th. Based on the iPhone I wouldn't be surprised to see it show up on Thursday, but I won't hold my breath, either (when it comes, it comes).
Those of us who did get delivery confirmation of the 16th should be very happy, as now online orders are being pushed back by as much as three weeks (and it will only get worse). And trying to stand in line for the (few?) available in stores on Friday? Forget about it.
(My only sadness is that I shippped my iPad 2 back on Friday for sale to eBay and now I'm iPadless for the next four days. I think missing an iPad is MUCH worse than if you had never had one before. I'm having major withdrawal symptoms from my favorite buddy, and my Macbook Air and iPhone are poor substitutes).