President Obama writes for Time Magazines "100 Most Influential People" list (which, of course, he also appears on).
Is it really true? The vast majority of his wealth? The majority would be >50%, but what's the vast majority? That would have to be something upwards of 90%, right? Buffet's given that much of his money away? Or does the truth of the statement depend on the meaning of the word "devoted"? A big old capitalist could claim that investing in your own burgeoning business is devoting your wealth to the greater good. And there's also room to maneuver inside the phrase "those... in need of help." Your friends and family and you yourself need help, right?
ADDED: Based on the comments to this post and a quick read of the "Philanthropy" section of Buffet's Wikipedia bio, I can see that the "devotion" to which our President refers is Buffet's announced plans for what will happen to his money after he dies. Buffet doesn't "believe in dynastic wealth." And there's also the "Gates-Buffett Giving Pledge," which is a pledge — not a legal obligation — to give at least 50% — the majority, possible not the vast majority — to charity. But Buffet has made statements of intent to leave 99% of his wealth to charity.
In the comments, Hoosier Daddy says: "Anyone ask Warren why he's not donating his wealth to the IRS rather than some private charity?" Quayle says: "So if Buffet voluntarily devoted his wealth, why do we need the government to take wealth by force?"