I don't know why but in the past two months, two online fiction magazines have non-fiction articles on tabletop RPGs.
The first (which I missed when I first looked at Strange Horizons earlier this week) is Lingua Rpga and the Writer by Steve Berman. Here, he gets testimonials from authors like Holly Black, Will Ludwigsen, Cecil Castellucci, and Jim Hines on their experiences with D&D. [Link courtesy of Matt Staggs.]
The second is from Clarkesworld two months ago. Justine Howe and Jason S. Ridler interview a variety of authors and get the pros and cons of the influence of RPGs.
While I'm at it, I'll throw you a bonus deal as well. Local author Dean Alfar shares his gaming experiences and how it has helped not just his writing but his business as well.