Personally, I think that the changes they've made in these beta are enough to make it intuitive.
With the added arrow and the much more prominent and frequent 'slide to unlock' pulse, plus the way that the on-screen elements bounce (as though being pushed right) when you tap the screen, it now makes it very obvious that you're meant to slide right.
I think adding a box around the text would be counter-productive, since iOS 7 allows you to slide to unlock anywhere on the screen.
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I think having the little bars is better than nothing. At the very least, it gives the user a target to interact with. With a little trial and error, the chances are that most people will quickly realise what you're meant to do with them.