Emily Nordling has never met a Muslim, at least not to her knowledge. But this spring, Ms. Nordling, a 19-year-old student from Fort Thomas, Ky., gave herself a new middle name on Facebook.com, mimicking her boyfriend and shocking her father. “Emily Hussein Nordling,” her entry now reads. With her decision, she joined a growing band of supporters of Senator Barack Obama, the presumptive Democratic presidential nominee, who are expressing solidarity with him.....