When TV mega star Oprah Winfrey isn’t dishing with Rielle Hunter on the private lives of former presidential candidates, she has something else on her mind: text messaging. Specifically, she’s waging her own one-woman (albeit with a pretty power megaphone) campaign to stop drivers from texting and using cell phones while driving. And she wants more people to sign up for her “No Phone Zone” pledge. The national event Friday found a local angle…