I have seen this problem in Yahoo! Mail and Netflix.
When clicking on some elements (in case of Yahoo Mail they are table cells) the focus ring is shown. This behavior did not exist on Safari 3.1
I am attaching a couple of screenshots where I have seen this problem.
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Yahoo Mail Table Cells
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NetFlix movie rates
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Yahoo Mail Options
<rdar://problem/6083514> REGRESSION: Focus ring being shown on some html table cells
could have something to do with allowing tabindex on all elements, which makes those elements focusable
I was looking at the places where I see the ring in Yahoo Mail, and Netlflix and all of them have tabIndexes, although the cells in Ymail's inbox have tabindex="-1"
Using the inspector, the yahoo mail message fields are focusable because they are table cells with tabindex=-1.
I haven't looked into the other 2 cases, but i suspect they are similarly behaving correctly. please inform me if i'm wrong.