Does Rockabye Baby!, a company that produces and sells “lullaby renditions of baby’s favorite rock bands,” have to seek permission from the bands themselves in order to create and market their products? Rockabye Baby! (the exclamation point is in their name; don’t worry, I’m not that excited about them) sells baby-safe versions of the music of a variety of rock artists, from AC/DC to Zeppelin. My fiancee and I recently gave their “Pixies” CD to the indie-rock loving parents of a newborn. They were excited to receive the CD, and we all enjoyed listening to the mellow instrumental take on…