Can't see a post about this yet, but when trying to sign in after installing the 7.0.0.3 hotfix update, I'm in the queue for a bit, but then get kicked out with an error message saying that Destiny servers are not available. Check that you have the latest version installed.
I'm confused about the timeline of the update. Details on Twitter and the Forums say that the servers should be available again by 9am PST, which is 5pm GMT (here).