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
There is no specific image name. Having the Default-568h@2x will launch that image on an iPhone 5 or iPod Touch 5G and will enable the non-letterbox mode. After that, you need to design your views to be flexible. There is no special "image name" or anything for the new size.
For your background, for example, you should probably be using an image that is capable of stretching or tiling and have it configured properly before setting it.