First Lady Michelle Obama joined Pinterest today, and already has more than 5,000 followers on the site. She has used the service to pin photos from Father's Day, her wedding, and other events around the White House. All of Michelle's pins and captions are signed "-mo," but the account is run by the Obama 2012 campaign staff, possibly to reach site's primarily female audience. Barack Obama joined the site in March, but the Obama Campaign isn't the first to use the service to reach out to voters — Ann Romney, wife of Republican Presidential Candidate Mitt Romney, joined in February.