I don't get it - how can W. Gates III still be "the world's richest man" with a NW around US$50b, when this appears to still count the $25b or so he donated to his charitable trust a couple of years ago?. Surely his net worth is now "only" $25b or thereabouts?. Either the money is still his, or else he's donated it to the trust and it isn't "his" anymore (even though he may have legal interest in the assets, they are for the benefit of the trust).

Year NetWorth (Forbes) in Trust (total)
2001 $58,700,000,000 n/a
2002 $52,800,000,000 n/a
2003 $40,700,000,000 $24,000,000,000
2004 $48,000,000,000 $27,000,000,000
2005 $46,500,000,000 $27,000,000,000
2006 $50,000,000,000 $29,000,000,000

A quick look at the Microsoft share price since 2001 shows that his net worth probably dropped from $52.8b in 2002 to $40.7b the following year - so he didn't suddently have an extra $24b to donate into his charitable trust - it must have come out of his net worth.