Warren Buffett, chairman and CEO of Berkshire Hathaway, sits in front of a Forbes Magazine which lists the top 400 wealthiest Americans, before speaking at a Senate Finance Committee hearing about ''Federal Estate Tax: Uncertainty in Planning Under the Current Law'' on... REUTERS/Jason Reed Billionaire Warren Buffett on Wednesday endorsed the estate tax as a check on wealth accumulation, while two senior U.S. senators said they want the tax repealed. Revisiting a long-standing debate over the...