Nice work, Steve Jobs!
It's great to see Steve Jobs moving up this list. He's certainly had a busy life and his foresight, leadership and entrepreneurial spirit have earned him a top spot. I'm a freak for Apple's products and it's silly, but my life feels richer from having them. I don't say that about many of my possessions.
Bill Gates is incredibly generous with his money and I think that's great. He's an amazing man and Microsoft is an amazing company. Mr. Gates may solve many of the world's problems with enormity of his charities.
That said, believe it's up to each person to give, privately or publicly, whatever they want. While I think it's fantastic for a person to give to charity, I certainly don't believe they have any sort of obligation. I'm an atheist and believe that if you get to your station in life through good luck or hard work, then that is your own. You don't owe the fates or anyone else if you are successful.
If they only give 1% of what they make, they've still contributed more to charity/society than any of us. We shouldn't get to judge these people because we were lazier and don't make enough to give much. Trust me... as hard as you work, most of these billionaires work WAY harder and the stakes are much higher. Thousands of people's livelihoods depend on every decision these guys make.
If you read the biographies of any of these people, you'll see that they had more drive than any of us and made good on the ideas they had. Sorry about the soapbox, but I've just seen too many people who give nothing complaining about the "just a couple million" that someone else gave.