A billion dollars just doesn't go as far as it used to. For the first time, it takes more than $1 billion to earn a spot on Forbes magazine's list of the 400 richest Americans. The minimum net worth for inclusion in this year's rankings released Thursday was $1.3 billion, up $300 million from last year. The new threshold meant 82 of America's billionaires didn't make the cut. Collectively, the people who made the rankings released Thursday are worth $1.54 trillion, compared with $1.25 trillion last year. The very top of the list was unchanged: Microsoft Corp. founder Bill Gates led the list for the 14th straight year, this time with a net worth estimated at $59 billion. He was followed by Warren Buffett of Berkshire Hathaway Inc. in second place with an estimated $52 billion. The list showed some notable changes. Joining the top 10 of the country's richest for the first time were Google Inc. founders Sergey Brin and Larry Page, who tied for fifth place. The 34-year-old moguls' wealth has quadrupled since 2004 to an estimated $18.5 billion this year, while their company's stock value has surged 500 percent. Lower down, almost half of the 45 newcomers made their millions in hedge funds and private equity investments. Wall Street really led the charge this year," said Matthew Miller, editor of the Forbes list.