I asked around, and according to my sources, it is too good to be true: the iPad 2 does not have a retina display. I believe the iPad 2’s display will remain at 1024×768. Its display may be improved in other ways — brighter, better power consumption, thinner, perhaps. Maybe it uses the new manufacturing technique Apple introduced with the iPhone 4 display, which brings the LCD closer to the surface of the touchscreen glass — making it look more like pixels on glass rather than pixels under glass. But my sources are pretty sure that it’s not 2048×1536 or any other “super high resolution”.
But so what’s the deal with those double-resolution UI graphics in iBooks? I don’t know, but my guess is that it’s just the work of a UI designer thinking ahead. Sooner or later, the iPad will get a retina display, and I remain convinced that it will be exactly double the current resolution. (There are 2048×1536 iPad prototypes in Cupertino. They’re not the iPad 2, though.) Double-resolution graphics created now are double-resolution graphics that don’t have to be created under a tight deadline later, when such an iPad actually ships. (I suspect it’s an oversight that these graphics were actually included in the app bundle at this point.)
At this point, one can not be sure whose claims to deem right as there are just too many rumors floating around. Let us wait on the next round of rumors to make it clear if the iPad 2 will have the Retina Display. We shall definitely update you when that happens.