With the retina we make images with the @2x in the name. I see where the default image has to be default-568h@2x but this does not seem to be the case for other images. Like
To complete Jason's answser, I would propose: What about overriding the UIImage's imageNamed: method to have it happen the "-568" suffix to the name of your image? Or add a new method called resolutionAdaptedImageNamed: to the UIImage maybe using a category.
If I have a bit of time in the next days, I will try to post the code for that.
Caution: will not work for images in the Nib files.