Nexus 7 tablets are now shipping.

Finally, eh?  Google's Nexus Twitter account just announced it was starting to ship Nexus 7 tablet orders:

Locked and loaded, ready to play: we’ve started shipping +Nexus 7 pre-orders today! google.com/nexus/#/7
— Google Nexus (@googlenexus) July 13, 2012

On the Nexus 7 tablet help page, Google has changed the notification to read:

When will my preorder ship?

We're now shipping Nexus 7 preorders. The first wave of orders are going out today and all preorders are scheduled to ship within the next 3 business days.