Former Speaker of the House Newt Gingrich announced on Saturday that he would not be running for President of the United States, effectively locking in the shape of the 2008 field. With Gingrich, the last fence-straddler, out, and Fred Thompson finally officially in, the preliminary warmup stage is complete. The real race has begun. Consider this all-politics Sunday Show Roundup episode of TPMtv the starting gun, or perhaps the starting-of-the-sprint-to-the-start gun …