Mark Kleiman argues that Obama does deserve his Nobel, because
The Non-Proliferation Treaty commits its nuclear-power signatories to work toward the abolition of nuclear weapons. Under Cold War conditions, that goal seemed merely aspirational, with no immediate practical implication.
But after the Cold War, with U.S. conventional forces overwhelmingly superior to those of any potential rival, it became very much in the security interest of the United States to reduce or abolish nuclear weaponry, and Bill Perry, Sam Nunn, Henry Kissinger, and George Shultz proposed exactly that.
Last month at the U.N. Barack Obama committed the United States to that program, which (among other good effects) strengthened our hand against Iranian and North Korean proliferation efforts; it was hard to denounce their violations of the NPT with a straight face when we weren't even pretending to try to live up to ours.
Hmm. Well. Call me crazy, but I think that maybe to earn the Nobel prize, a million dollars, and all the associated prestige, you ought to have made efforts somewhat more heroic than chairing a meeting in which you said that you thought we ought to have fewer nuclear arms--even one in which you said that the US also thought we ought to have fewer nuclear arms. You should, I don't know, deliver a deal or something.
As for the notion that this strengthens our hand when dealing with Iran and North Korea, I'm really skeptical that this does anything at all. The leaders of Iran and North Korea do not, to put it mildly, look up to us. They don't want us to think that they're nice, moral people. They want us to think that they are terrifying military forces whose desires must be assuaged. The people of North Korea and Iran don't like us either, but even if you thought that this was likely to have a big impact on their opinion, this would be purely hypothetical, because both countries have very tightly controlled media which will report whatever the leaders want them to think.
If the best you can come up with is that he made some impressive-sounding statements at the UN--well, I think a majority of the world's leaders are equally deserving. I don't see any actual foreign policy scholars advancing the theory that this was a landmark achievement on par with say, SALT or the Camp David accords.