I pretty much agree with the original list.
To those who think Bush and Olmert should not be on the list, I reply: The topic of the post was not "which people are the most evil persons on earth" but "which persons are most dangerous to mankind". Now I don't think either Bush or Olmert mean harm by what they are doing, they probably are even idealistic people. However, the saying goes "The road to hell is paved with good intentions", and George W. Bush seems to be a prime example for that.
As I see it, Bush simply doesn't quite grasp the long-term consequences of his actions, in particular of the wars he started. The invasion of Iraq has now led to thousands of dead American soldiers, ten of thousands of dead Iraqi people and wide-spread antagonism against the American people, especially among muslims. Before the war, Bush probably thought that the military conquest of Iraq was a non-issue (in which he was mostly correct), that the Iraqi people would welcome him with open arms when he rid them of Saddam (he was only partially right in that) and that his troops could soon leave after he set up a democratic government there (in which he was completely mistaken).
That last error cost America greatly and in itself completely justifies Bush's place on this list. To those who think every rapist and murderer is more evil than Bush, yes I agree, but that is not the issue here. Thoes rapists and murderers do not have the position of power and responsibility that Bush does, and thus are not as dangerous to the human race.
To the topic of the others on the list: Olmert, in my opinion, is much the same as Bush, just on a smaller scale, since Isreal simply doesn't have the power to do as much harm as the US.
Osama Bin Laden is rightly on the list: Many will call him evil, I'd call him psychotic: He believes what he's doing is right, which makes him all the more dangerous, since so many muslims who feel themselves wronged listen to him.
Kim Jong Il is the one on the list I'd say fits "evil" the most, since he knows exactly how much his people suffer and still wallows in his luxuries. Calling him dangerous because he's a "communist" is a laugh though: Communism is based on the idea of equality of all people, which is lightyears from what the situation in North Korea actually is. He is dangerous because of the power the bomb gives him, because he has unchecked power in his own country and because he seems to revel in that power and leaves out no opportunity to provoke his neighbor nations, which could one day blow up in his face.
Finally, Vladimir Putin is, of course, also very dangerous as the dictator of the country with the second largest nuclear arsenal. My perception of Putin is that of a ruthless, very smart person. Because of that, he is extremely dangerous to his own people, whose freedom he is taking away step by step these days. However, I very much doubt he would ever let Russia become involved in a nuclear war, he is too smart for that.
Summing it up, I think the greatest threat to the world at the moment is George W. Bush, not because he is "evil", but because he is sitting at the largest nuclear trigger and, IMHO, doesn't have the mental qualifications to use that power responsibly.