I'm surprised at the size and scale of that structure too be honest, I didn't realise it would be so large! My guess it, part could be a stage, part could be a product demo area.
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I think the fact that there is such a large, well known band, such as U2 performing, could indicate something music relating happening. I really wouldn't be surprised to see an iPod update.
Nothing major, but something like.
iPod Touch - A7 Chip, Touch ID, New Camera, 128GB
iPod nano - Maybe staying the same, or a slight update with an iOS 7 interface.
iPod shuffle - No update
iPod Classic - RIP