Our advice? Don't panic. Until your item specifically ships, it's not unusual for the Item Status field to reflect the status of the item in general and not your copy in particular. The Backordered status refers to their stock as a whole, meaning overall they've hit the Out of Stock point. The copy you ordered may be just fine and dandy and you'll probably see your Status flip to Pending or Shipped at some point throughout the day. If you ordered your copy early, you are most likely completely safe and fine. If you ordered it very very late, it's a little more likely that your personal order will be affected, but chances are still very good that you'll turn out okay.
It's a weird system. When that Backordered label crops up, it's hard to tell whether your copy is actually going to arrive at your doorstep or not. It's not a completely unusual occurrance, it happens now and then with really big releases. It's just as confusing each and every time. Just relax, keep an eye on it, and don't worry too much until it still says Backordered tomorrow morning and your copy hasn't shown up on your doorstep. Then you might have a problem.