The current icon is incredibly bad, in my opinion. The artwork should be one or the other; not a merge of both. The power button icon wouldn't be the best choice (since it contains more than shut down options), so just a plain gear would be fine. Looks good that way in the Faenza icon theme.
I also agree with ELD- the icon looks like a button that does something entirely different on another mainstream OS. Might be a great way to cause confusion, especially given that they'd be in the same place on the screen.
Oh well. I'm just waiting for the new icons to begin rolling out