Coraline is designed to be shown in 3-D, but movie theaters are badly behind schedule in their plans to install the necessary equipment. According to Bloomberg, only about 1,400 theaters in the USA and Canada have the added equipment necessary for 3-D.
Here's bootleg video of a 3-D preview of Coraline. You can hear the crowd "ooh" in appreciation:
And here's a higher quality version of the 3-D trailer:
Of course, I've also read that the 3-D elements are "fine" but unnecessary to the movie, so don't worry too much if your town doesn't have a 3-D enabled theater.
*Buy 3-D books and comics at eBay.