Not sure, but if you can see it, the area surrounding that bit is stamped over the top of the UI in a sense, making that element larger than it initailly appears, fwiw. Granted, it's still pre-release and may have nothing to do with anything/may be cleaned up in final. Or could there have been more to show (perhaps some text labels) and it was 'shopped and edited before he published his blog?

For being more fingertouch-centric, if it is an eq or vu meter or similar, it would seem it is either a minimized app/gadget that when touched will bring up the full app or it's simply meant to overlay and be viewed as is. (captain obvious award?)