The DS is purportedly bringing in new gamers who wouldn't traditionally care about video games at all, with stuff like Nintendogs, Brain Age, and Personal Trainer: Cooking (as seen in the above ad). We're happy to see Nintendo capturing the interest of people who previously would have seen our hobby as either too kid-oriented or too teenage-dude-oriented.
Have you seen it work? Have you encountered the "expanded audience" out in the world? Become acquainted with any new DS owners lured in by language training or math? For our part, we seem to be meeting more late-to-the-party gamers than ever these days (in our limited capacity as socially inept shut-ins to meet people).