According to Pwinsider.com, WWE debuted 24 year old Lauren Mayhew as a new ring announcer at last night’s Smackdown taping in Tulsa, Oklahoma. Speculation is that she will stay on Smackdown, while one of the more "tenured" announcers will move to Raw.
According to her profile over at IMDB, she has a lot of TV experience, working on CSI: Crime Scene Investigation, American Dreams and The Guiding Light.
(you can see two videos and a picture of Lauren Mayhew at the source link provided)