Well, That Was Obvious

Obama probably knows that McCain has nothing but dripping distain for him. He knows this and he still offers his hand to McCain.

Perhaps it a "southern" thing, but when a man "offers his hand" to you, it's a sign of solidarity, a sign that you have respect, and often a physical statement meant to convey an apology - like "sorry I was so hard on you, but you deserved it".

McCain knows he's been beaten and refuses to conceed.