Am I the only one who has noticed the awful design of the dialog?
a) The red stop icon is way overrated for this kind of alert. The yellow triangle would be more fitting. The current icon looks way too "scary" to the normal user, and would trigger concern that something was seriously wrong.
b) Every Word Begins With A Captain. Doesn't look very OSX-like, and not very user-friendly as well. Looks like the dialog and its' way of presenting the information is for advanced users, not "streamlined" for regular users to understand what's happening. It's also not very professional-looking - no question mark at the end of the question. A better way would be to word it like this:
The following application, Sample Application, is requesting access to your contacts list. Do you want to allow Said Application to access your contacts list?
Don't Allow | Allow
c) Yes, I know, it's a developer's preview, blah blah blah, but what if Apple leaves the dialog as it is for final release? I have a bad feeling they will, because they didn't revise it for the Dev Preview, so there's no sense of polish with the dialog at all, and it somehow comes across as "final-looking." Hard to explain, but it just seems like Apple's became more and more sloppy with OSX polish lately.