Matthew Panzarino for TNW:

Now, with the release of the iBooks 2 application, the Retina-ready images are on display yet again, but our source says it is highly doubtful that including them this time is an accident.

These images would display correctly on a screen 2048×1536 pixels in dimension (double the res of the iPad 2′s screen) at a PPI of 260. That is lower than the iPhone 4/4S display, which clocks in at just over 300 PPI, but should still qualify as a Retina display due to the viewing distance to the iPad being greater.

These @2x files appeared in a version of iBooks during August 2010 but turned out to be a red herring (or an accident as TNWs source puts it). However, with rumours ramping up for a March launch of the iPad 3, it’s highly likely that these retina display graphics are now needed.

The thing that confuses me is that iBooks doesn’t come pre-installed on iOS so Apple could easily push out a v2.0.1 safe in the knowledge that a non-retina version wouldn’t end up on the new iPad. This is undoubtedly what will happen with the iWorks suite of apps (a minor update to add retina compatibility) so why add @2x versions of UI components to iBooks now?

In my opinion, this was either a mistake (again) or Apple are planning on having iBooks installed by default on the iPad 3.