Are iBook 2's High-Res Images Meant for the iPad 3?

Apple's iBook 2 app comes with some interesting media bundled in it. Developers have uncovered high resolution images that seem designed for use in a Retina display but the iPad 2 doesn't have one. Is this evidence that the iPad 3 will?

The pictures are denoted with "@2x" in their filename and at, 2048×1536 pixels, they are double what the iPad 2 can natively display. What's more, they display at 260 pixels per inch (PPI). That's not quite the 300PPI that the latest iPhones can do—and what Apple has said officially constitutes a Retina display—but still dense enough to fool your eyes at the increased viewing distance.

This isn't the first time that Apple's leaked @2x pictures. An earlier version of iBooks (version 1.1) included similar pictures back in 2010, which lead to speculation that the forthcoming iPad 2 could have a Retina display. So, is Apple prepping for a surprise iPad 3 launch or is someone on the iBook development team just having a bit of fun with us? [MacRumors - Top art adapted from screengrabs on 9to5Mac]