Two top San Francisco Examiner editors have left the paper for a new media venture -- a magazine for the Web. David Talbot, assistant managing editor for arts and entertainment, and Foreign/National Editor Andrew Ross aren't talking about their new project yet, and refuse to confirm that some of their seed money came from Apple computers. ... "The Largest Newspaper in Northern California," our beloved San Francisco Chronicle, has dipped below the 500,000-circulation mark, according to a news story appearing in its own pages last week about the sale of Lesher Communications. The Chronicle's circulation now stands at 499,526, which will soon be corrected to 499,527 because Chatterbox started subscribing to "The Voice of the West" late last month, and fervently hopes that the Chron locates 74 more readers to put it above the magic 500,000 mark. ... The Golden Gate Bridge District's plans to serve commuters with catamaran ferry service between Larkspur and San Francisco would have a better chance of succeeding if it deliberately evoked the obvious Waterworld comparisons: Imagine, restrooms that recycle bodily fluids, guest appearances by Dennis Hopper, and slap-on gills for particularly wet crossings.