Amidst the swirl of rumors surrounding the iPad 3, one has remained nearly constant: retina display. When the iPhone 4 debuted with the high-res retina display in the summer of 2010, most assumed that Apple would immediately deploy the same remarkable technology on the iPad 2, which came out the following March. The iPad 2, however, launched with only a slight improvement in resolution over its predecessor. Ever since, it has been widely assumed that whatever technical limitations prevented the retina display from coming to the iPad 2 would be overcome by the time the iPad 3 launched.

Yesterday’s launch of iBooks 2 appears to have offered come confirmation of that rumor. Developers digging through the files for iBooks 2 found a series of images – book covers, bookmarks, and the like – that were much higher-resolution than the iPad 2 requires. Similar images had been found in older versions of iBooks, those were apparently placed in iBooks by accident by an Apple employee who had worked primarily with the high-res files required for the iPhone 4’s retina display. These images are new, however, and appear among the older high-res files. Unless another accident has occurred at Apple, the inclusion of these high-res images in iBooks 2 strongly suggests that the iPad 3 will have retina display. Sonny Dickson posted an example of the kind of high-res images that are new to iBooks 2 on his Twitter account last night. Check out the images and the tweet below.