This is not to dismiss the likes of Bill Gates: he has been very public with his donations, but in some cases (notably celebrity) notoriety in your donations may create a multiplier effect as it encourages others to do likewise. Even so, I think this is still on a lower-rung, philanthropy-wise, than Feeney's approach.
Nonetheless, we're sitting here praising someone who reduced himself from billions to $2M, but we must remind ourselves that this is unimpressive compared to the poor person who donates $25 to others while starving herself. The value of money is nonlinear. I'm sure that Feeney would say this as well: he no doubt sees himself as saddled with the burden of billions of dollars rather than someone doing something amazing.
I wonder if I ever will have the strength to do what he has done.