Most of the books that I get that are shrink-wrapped, are special press (Gauntlet, Cemetery Dance), special or limited edition, and or signed by the author. I mainly do my book shopping through B&N.com, and this is usually the case as well. I've never gotten a normal edition shrink-wrapped, but not all the signed editions are shrink-wrapped either, Edward Lee's books for example aren't always wrapped, and sometimes when they are, they aren't signed editions at all, but most of them are, if they aren't mass-market.