Former Speaker Newt Gingrich said Tuesday that he thought Senator Hillary Rodham Clinton, Democrat of New York, would be her party's presidential nominee in 2008 and that she would be "very formidable." He said she might even win. Mr. Gingrich, a Republican, was addressing the American Society of Newspaper Editors here and was asked if he might challenge her for president in 2008. He did not answer that question, but it was clear he had been watching her. "Senator Clinton is very competent, very professional, very intelligently moving toward the center, very shrewdly and effectively serving on the Armed Services...