It means they have assigned a car to you. Hang tight, for me it took a half day to show up on the page. Roughly around the time I got the delivery call.
@tuffcalc, it took about a week from the time I first found my VIN in the source code to when it showed up officially on my account page. That last step normally occurs when your MVPA appears in your account. Before the VIN was officially on my page, I called my delivery center and they confirmed that a VIN was assigned to my car and that it was in the "pre-production" phase. I'm taking delivery of the car tomorrow, 1 week after seeing the MVPA in my account and 2 weeks after I first found the VIN in the source code.