Justin Bieber
With the appearance of Miley Cyrus and Boyz II Men at Justin Bieber's Madison Square Garden show earlier this week, the 16-year old superstar's special guests may have surprised the crowd, but weren't exactly sonically incongruous shock appearances. But for those not familiar with Bieber's recorded output, the emergence of rapper Ludacris, who appears on on "Baby" off Bieber's 'My World 2.0' album, may have left some wondering if he had the right building. The relationship further solidifies the relatively recent BFF relationship between hip-hop and teen pop.

For most of the 1980s and early 1990s, the intersection of the two genres was virtually nonexistent. In 1989, you weren't exactly finding a lot of fans of both New Kids on the Block's 'Hangin' Tough' and Eric B. and Rakim's 'Follow the Leader.' This wave of teen pop was displaced, in part, by the proliferation and commercial acceptance of gangsta rap in the early '90s. When the boy band explosion of 'N Sync, Backstreet Boys and the like erupted a decade later, rappers understandably kept their distance. Fanbases couldn't be alienated or compromised and syrupy teen pop music was worlds away from the bravado and chest-thumping that characterized many hip-hop artists.