DragonBelow
Adventurer
It's about e-books in general but mostly discusses the RPG section as a success story:
http://www.biz-journal.com/articles/2007/12/10/national/doc475b7b15936be394548985.txt
http://www.biz-journal.com/articles/2007/12/10/national/doc475b7b15936be394548985.txt