In the UK, your Nexus 7 will have shipped by July 20 as long as you ordered it before June 30, but customers who ordered the 16GB model after that date will have to wait until next week. All Australian orders will be shipped by July 19, and while all 8GB orders have shipped in Canada there'll be a 1-2 week wait for the 16GB model. Google is also allowing for the possibility that these times won't hold true for everyone, and urges those affected to contact the support team. Of course, those making new orders today will still have quite some time to wait regardless, but at least it looks like the earliest adopters should be dealt with soon enough.
Google clarifies status of Nexus 7 pre-orders (update: 8GB model in stock now) | The Verge