According to this article the President signed into law a provision that allows tsunami donations made in January 2005 to be a deduction on 2004 taxes.
While it is an individual's choice to donate to charity, and where to donate if they choose, but there's no doubt that the tax breaks for charitable giving have a direct impact on a lot of people.
With any luck this move will trigger an increase in charitable giving for the tsunami - further damping the claims that America is stingy when it comes to charity.