Portfolio.com is adding yet another blog to its Web site, Playas (yes, Pla-YAAHS). The weekly blog will feature contributions from celebrities and executives, and appear on the site every Thursday. Each blogger will post about a half-dozen entries during his or her Thursday appearance. Movie producer Harvey Weinstein will be the first to blog on Playas today, followed by Playboy Enterprises chief executive officer Christie Hefner, author, entrepreneur and chess expert Bob Rice and Ford Models ceo John Caplan. Few guidelines have been given to the guest bloggers on their topics of conversation, but Dan Colarusso, portfolio.com managing editor, is confident each will keep visitors engaged. “If Harvey decides to talk about the movie business, about the fashion business or about politics, he’s going to strike a cord with other like-minded execs who aspire to be Harvey Weinstein.” Or not.