The most powerful player in the book business besides Oprah,, just got a little more powerful with the acquisition of Shelfari, a social network for bookworms. Not yet formally announced, the deal would give Amazon total control over a competitor to a similar site, LibraryThing, in which the company has already taken a stake through an earlier acquisition, according to Seattle Post-Intelligencer reporter John Cook.It makes sense: Why pay to develop your own social software when you can buy up existing technology and communities of potential customers as well? Never mind the apparent conflict of interest, or Shelfari's spammy history. Those concerns are for companies who aren't trying to corner nascent markets through vertical integration. (Photo by Tim Mansfield)