Gates retains 'wealthiest' crown

Tech industry billionaires dominated Forbes' latest list of the United States' wealthiest people, with Bill Gates and his $51 billion fortune again topping the list.

The Microsoft chairman has now been top of the tree a dozen times. Co-founder Paul Allen, worth $22.5 billion, again placed third, while CEO Steve Ballmer, valued at $14 billion, nabbed the No. 11 spot.

With the exception of legendary investor Warren Buffett, whose $40 billion net worth secured him a spot behind Gates, this year's top five wealthiest Americans all represent the technology industry.

Michael Dell and Oracle executive Larry Ellison, with their fortunes pegged at $18 billion and $17 billion, respectively, both beat out a handful of Wal-Mart heirs to take the fourth and fifth spots.

Google founders Sergey Brin and Larry Page -- each worth $11 billion and, at 32, the youngest of the pack -- surged to the No. 16 spots after debuting on last year's list at No. 43. They displaced 38-year-old Pierre Omidyar of eBay, who, at $10.2 billion, placed 18th.

Google is doing a lot of displacing these days. Brin and Page are the young lions of the tech industry, while Gates and company increasingly are becoming the old guard. The battle between Google and Microsoft isn't just over the wealth of employees but also extends to which company will dominate in the early years of this century.

Amazon.com's Jeff Bezos, who recorded $4.6 billion, slightly more than last year, dropped from No. 38 to the No. 42. Apple's Steve Jobs, as well as Yahoo's David Filo and Jerry Yang, also made it into the top 100.

Overall, the total net worth of the Forbes roster grew to $1.13 trillion. All but 26 people on the list -- including AOL co-founder Steve Case, ranked No. 384 -- counted their net worth in the billions.