Let me just say up front that I voted for Barack Obama, and I admire and support the man and what he is doing (with some caveats). However, he is no Gandhi. We're not out of Iraq. We're not out of Afghanistan. Guantanamo isn't closed. We still hold people without due process. Our security apparatus still has programs in place that violate the constitution and basic human rights.
The main reason that he looks like he's doing so much to create world peace is that the Bush administration (if it can even be called that) took the United states so far away from the norm, so far out to extreme positions that just to bring us back to a "normal" posture looks radical by comparison. Has Obama really done anything different than Bill Clinton did in his years as president and afterward with his Global Initiative? Carter had to toil for decades before finally being awarded the prize. Obama has been president for 9 months.
Are there better, more deserving candidates? I'm not sure, I don't really follow the process. But a few people/organizations come immediately to mind. How about Bill Gates (and Melinda) and Warren Buffet for creating and funding the $70 billion Bill and Melinda Gates Foundation, the largest privately funded humanitarian organization in the world? How about Habitat for Humanity which has built housing for over a million people worldwide, thus alleviating suffering and promoting stability. How about a modern day version of Irena Sendler like Hotel Rwanda's Paul Rusesabagina?
If Barack had halved the US nuclear arsenal, forged a lasting peace deal between Israel and Palestine, or closed half of the US overseas bases, I could see it. But right now, I'm just puzzled.
UPDATE: Glenn Greenwald and Naomi Klein put this more elegantly than I could.