We've seen versions for the MacBook Pro and the MacBook Air in the past. Now, Twelve South has taken its popular design to BookBook for iPhone 4 ($60). It's hard not to get a kick out of the leather bifold-wallet and case combo; it'll certainly be a conversation starter. A frame on the right holds the iPhone 4 in place, with cutouts along the bottom and top for access to the ports and buttons. Both volume buttons are covered, and the side switch is…
