What is Ann Romney hiding? Barack Obama, Michelle Obama and Mitt Romney have all disclosed, but so far an exhaustive search — okay, it was two minutes on Bing — has revealed that Ann Romney is withholding important information. What is she not telling us? Her iPod  playlist.

Ever since Bush's media guru Mark McKinnon was smart enough to release George W.’s playlist for his grueling mountain bike workouts, it has been a staple of presidential candidates to release their own version.

Candidate Obama revealed his in 2008 to Rolling Stone, an eclectic list in keeping with his own multicultural fluency. On Monday, Michelle Obama released her workout list, which implies her workouts are a little short, but extremely energetic. Mr. Romney revealed his playlist recently as well — and not to be mean, but the playlist in my local Safeway is better.

So far, nothing from Mrs. Romney, despite the fact that she has her own customized iPod cover, which is becoming a preferred fashion accessory to be sold on candidate Web sites, and her own Google Adwords buy, soliciting campaign donations under the pitch, ”Stand with Mitt’s better half.” So she isn't exactly hiding. And she has a golden opportunity to be Mitt's better half, musically.

One shouldn't make too much of these iPod playlists, although there are some potentially interesting differences between Obama’s playlist of 2008 and 2012, which I may probe at a later time. Mark McKinnon, who is a former songwriter and has a deep knowledge and love of music, responded best when people tried to analyze Bush's favorites: “Hey, it's about helping him climb the next hill.”