Diddy x BlackBook. In an effort to promote their iPhone application, BlackBook magazine has teamed up with Diddy. According to Billboard, BlackBook has partnered with the hip-hop mogul to create Diddy’s BlackBook. The guide offers Combs’ favorite U.S. hot spots as well as editorial reviews of 15,000 shops, restaurants and clubs across 50 cities worldwide. As part of the launch Diddy also graces the cover of this month’s BlackBook. Diddy’s BlackBook is available now on iTunes for free.