Sam Thompson is running 50 marathons in 50 days in 50 States. He began his journey on July 1, 2006 with the Leadville Trail Marathon and plans to finish August 19 in Mississippi.
According to CNN, Sam is trying to raise "awareness for the people he knows along the Gulf Coast who have largely been forgotten a year after Hurricane Katrina slammed the region."

The CNN story and a link to Sams Run For Hope website

Coincidentally Dean Karnazes is also planning a 50in50in50 starting on September 17 with the The Lewis & Clark Marathon in Missouri. Dean is planning to raise money for Karno Kids along the way. Karno Kids is an organization committed to encouraging young people to get outdoors and become more physically active. Deans final marathon is scheduled to be the New York City Marathon on November 5th 2006.

Deans Karnazes Blog
Dean Karnazes website