The mentality and treatment of Obama is not significantly different than what I remember seeing towards Bush. It's only, at most, a symptom of magnitude which is largely a symptom of societal advancements with regards to technology and the realities those impart than anything regarding race.
Debate Politics is a great example of this. The early versions of this forum weren't even in the heart of the Bush era, but there was still a staunch segment of crazies and hateful spiteful people that he could do no right with. The difference was that message boards weren't nearly as heavily visited as they are today and there wasn't nearly as many people across all age spectrums using the internet in such a fashion. That has significant changed now and it causes a very different atmosphere and presentation. But I don't think those people just didn't exist before, but rather simply didn't have the same outlets or the ability to be so loud with so many voices coming together.
The reality is that it's not race, it's politics. There's not a doubt in my mind that if Obama was a white guy from Kansas named Barry O'bannon that much of the same vitriol, negativity, and opposition would be occuring. Would some of the methods be different? Absolutely. Because once it's determined you want to tear the guy down...and that is determined, generally, because "He's of the opposite political party"....people generally go for the lowest hanging fruit.
It's "stole an election". It's "coke head". It's "monkey". It's "idiot". It's "cowboy". It's "daddy's war". It's "fascist". It's "nazi". It's "Talibornagin".
It's "not a citizen". It's "muslim". It's "doesn't like white people". It's "elitist". It's "socialist". It's "communist". It's "teleprompter". And on and on.
People, as a group, are generally simple tribal creatures. Identify the enemy, and then attack the enemy in the most expediant and simple ways possible. Not because any of those ways necessary actually bother you, but rather because they're the "enemy".
If Barack Obama was a Republican instead of a Democrat the vast majority of the critics of him today would have no issue with him and would likely actually be supporting him. That's a pretty good indicatoin that their issue isn't his RACE, but rather his political affiliation. There would be a small segment of the population that would still have an issue with him because they are real and true racists, but that part of the population is a small minority.
No, the Obama presidency is not proof that America is not "ready" for a black President. If anything, his election is proof that it is.