MOVIES: Which witch switch has played havoc in Hollywood?

  Too bad the editors of Entertainment Weekly don't have a clairvoyant on the payroll. Said soothsayer might have warned them of the dangers inherent in making "Harry Potter and the Half-Blood Prince" their cover story for their current fall movie preview issue.
  That's because Warner Bros., the "Potter" franchise's studio home, moved the saga's latest installment from its original Friday-before-Thanksgiving release date to mid-July of 2009, leaving EW with a cover story on a movie that moviegoers won't be able to see for almost a year. That's the kind of glaring error no wave of a wand can cause to magically disappear. (EW's "Harry Potter" stories are buried on its Web site, but for us old-media stalwarts, there's no mistaking owlishly adorable Harry himself, Daniel Radcliffe, peering from the current EW cover.)
  But one mystical movie's switcheroo is another's magical chance. No sooner had "Harry Potter" vacated the Nov. 21 release date than Summit Releasing swooped in to claim it for "Twilight," the first installment of a big-screen series inspired by Stephenie Meyer's best-selling books about a teenage girl (Kristen Stewart) who falls for a handsome vampire named Edward. Coincidentally, he's played by Robert Pattinson, who played Cedric Diggory in a pair of "Harry Potter" movies, 2005's "Goblet of Fire" and 2007's "Order of the Phoenix."
  It's a small big-screen world indeed.
  And stand by for even more schedule-switching in the coming weeks. After all, (Tom Cruise's World War II Nazi thriller "Valkyrie" also moved last week — to Dec. 29 from February '09. And there's undoubtedly more to come, as  studios try to pack more box-office attractions into fewer weeks left in the year.
  We'll explore the August version of all this schedule-switching, the weekly Wednesday opening, Friday in the Review-Journal's weekly Neon section. In the meantime, follow my example when you're filling in your moviegoing calendar — and use a pencil.