Mayor Gavin Newsom and his wife, Jennifer Siebel Newsom, popped out a 20.5 inch long, 7 pound 12 ounce baby girl today at 12:39 p.m.The baby, whose name was apparently being kept secret under threat of retribution, is Montana Tessa Newsom, named for the state in which the couple got married. (What if they had been married in Rhode Island?)Montana is in good company. At any rate, she has company. Other famous Montanas include:1. Hanah Montana (Miley Cyrus) who is part-rocker, part-regular high sc