He’s got some kinda tube on his head. and Obama has what looks like a chip clip oh his hand. What’s going on? Is this part of that secret Muslim-Jew conspiracy I keep hearing about from those nice bald boys down the hall? 
That’s the teleprompter in the left foreground.
Bloomberg & Obama are behind (part of) a teleprompter. What you’re seeing is a piece of plexiglas on a stand, angled so that when you stand in front of it you can see your speech being displayed on a TV screen sitting on the floor & angled upwards. From the side of the audience, it just looks transparent, and so the speaker can look out at the audience without it being obvious that he’s using a teleprompter. Usually there are two of them, in different directions from the podium, so the speaker can “dynamically” shift his or her gaze about the room rather than unnaturally staring in the same direction all the time.
ETA: Here’s a do-it-yourself project on how to build one with a laptop and a piece of glass, if my explanation isn’t quite clear enough.
MikeS is quite correct. Until a minute ago, I thought TelePrompTer was still a live trademark. A Wikioid tells me that teleprompter (in lower case) is a genericized word, and no longer a trademark.
Is Wikioid a word? It is now.
Boy, did I learn something from the board today. I always thought they were sniper bullet deflectors. Really.
Did you think they only sat the snipers in the sections of the audience off at those particular angles? 
No, there’s just a guy at the bottom holding it at the ready. If someone fires, he’ll move it to intercept the bullet.
He’s very fast.
I didn’t know what they were until I saw the movie Dave, actually. There’s a scene early on where the president (the real one) is giving a speech. The camera starts out facing him, on the side of the audience, and then dollies around to view him from behind, with the reflections in the teleprompters clearly visible.
It’s there for effect, like the pane of glass in bullet-catch magic shows.
“See? See? Must have been a real bullet, or the glass wouldn’t have broken!”
Obama is’t holding anything, except for Bloomberg’s shoulder. In front of his hand, in the way of the shot is a bracket that is holding the teleprompter screen.
Are you sure it’s not a sneeze shield? Bloomberg may be fine with black folks but secretly microbe-phobic.
This made me laugh.