Ordered 16GB on June 27th. Just got an email saying that my 16GB nexus 7 will be another 1-2 weeks before it even gets shipped. Yet, there is stock available at the local retailers. Cannot cancel. My advice - DO NOT ORDER FROM THE PLAY STORE. You will pay more (in shipping charges) and be one of the last people to get it. Never again will I order from the play store.
Hey Google, if you want to know how pre-orders work, look to how video game companies do it.