As one might expect, Thursday’s announcement that Bill Gates donated $5 billion to his family foundation made plenty of href="http://www.news.com/News/Item/0,4,37351,00.html?pt.salon">headlines. Not only did it vault the William H. Gates III Foundation to fourth place in the rankings of the biggest philanthropic institutions, with assets of $10 billion, but it is also believed to be the largest gift ever made by a living donor.

Eyebrows should be raised; Bill’s still a pretty young guy. For years he’s claimed that he would eventually give away the bulk of his wealth. If he lives up to his promise — and this latest gift suggests he may well do so — Gates may end up going down in history as the most magnanimous philanthropist of all time.

But where’s all this money really going? Here’s where the story gets href="/21st/feature/1998/01/cov_29feature.html">intriguing. Gates has gotten plenty of grief for the hundreds of millions of dollars he’s donated to his Gates Library Foundation; critics point out that it is obviously self-serving to stuff libraries full of computers running Microsoft software. But the William H. Gates III Foundation is a different kettle of financial fish.

The foundation is administered by Gates’ father, William H. Gates Sr., a longtime philanthropist who once served as a national board member for the United Way. His primary interest, as demonstrated by the grants made so far by the foundation, is in funding family planning and reproductive health programs — particularly in the third world. The foundation has also begun to spend aggressively on more general health-related issues — such as the search for AIDS and malaria vaccines.

Last year, Gates Sr. told Salon that administering the $300 million or so that was then in the foundation was “a hell of a lot of fun.” Now he has billions at his disposal. That’s more than just fun — that’s the chance to make a real difference in millions of lives.