Here's the website. This is interesting.
UPDATE: Here's a much better explanation from the San Francisco Chronicle:
Peterman -- former minor-league baseball player and longtime entrepreneur, now 62 -- found the famous coat, an ankle-length cowboy-style duster, on a trip to Jackson Hole, Wyo., and built a catalog around it in 1987. Larry David and Jerry Seinfeld, creators of the television series, became fans of the quirky writing and worldly voice that was J. Peterman, and in 1995 designed a character around it....
But even while "Seinfeld" was spreading Peterman's name, he was losing it. The company expanded rapidly in the late '90s, opening a chain of stores. Too rapidly, it had become apparent by the time J. Peterman opened on the first floor of the San Francisco Shopping Centre, in November 1998. By the next January, the San Francisco store had closed, the company went bankrupt and Peterman was out -- though his name was still in.
"The rapidity of the crash was amazing," he says. "And it was too bad. But we did a lot of things we shouldn't have done."
In the meantime, though, real Peterman had met fictional Peterman (O'Hurley) on national television, and, oddly, the entrepreneur and the actor who played a version of him became friends. Good friends. Good enough that the real Peterman says, "When the company went down, he had a bigger identity crisis than I did," then pauses. "That's a facetious remark."
Good enough also that when Peterman was ready to plunk down $1 million to buy back his name, he told O'Hurley, "I'm going to restart the company, do you want in?" The answer Peterman remembers: "Yep, how much?" And today, the fictional Peterman sits on the real Peterman's board.