By: Editorial Staff STEVE GREENBERG, cartoonist at the Seattle Post-Intelligencer, will be Editor & Publisher magazine's regular contributing cartoonist, beginning with this week's edition. Greenberg has been with the Post-Intelligencer since 1985. From 1978 to 1984, he was editorial cartoonist for the Daily News of Los Angeles. He has had cartoons reprinted sporadically in E&P since 1979. Greenberg, last year, won the Global Media Award on population issues, and is a three-time runner-up in the Free Press Association's Mencken Awards.