Who is the youngest athlete to win Olympic Games gold medal?

Through the 2008 Games in Beijing that would be Greek gymnast DimitriOS Loundras whose Greek team placed second in the parallel bars team event at the 1896 Games in Athens. He was 10 years, 218 days old.

In fact there was an unnamed French boy younger, just seven years:

http://en.wikipedia.org/wiki/Rowing_at_the_1900_Summer_Olympics#Trivia