I must admit that I thought this was a hoax when I first read the story. However, if so, it is a very elaborate one. The news story has been picked up and published by reputable news sources, including UPI, The Daily Telegraph, and others.
The story claims that Brothers Zsolt and Geza Peladi, who live in a cave outside Budapest and make money selling junk found in the street, said charity workers contacted them to inform them that they and a sister who lives in the United States are inheriting a $7 billion fortune from a grandmother who recently died in Baden-Wurttemberg, Germany.
The brothers stated that they knew their (deceased) mother was from a wealthy family but had no other knowledge of their relatives. The mother had severed ties with the family when she was young, then later abandoned her two sons. It is believed that the grandmother never knew about her grandchildren.
The lawyers settling the estate only learned of the grandchildren by carrying out genealogical research.
You can read more at http://www.upi.com/Odd_News/2009/12/02/Brothers-living-in-cave-inherit-fortune/UPI-53791259792028 and at http://www.ananova.com/News/story/sm_3584037.html.