iPhone 4 users have an edge over all the other iPhone users: and that is of having a Retina display screen. A retina display screen allows 4x the normal number of pixels in a screen, not only making the screen brighter, but sharper than anything we could imagine on a cell phone screen.
Click on each wallpaper for original iPhone Wallpaper size. If you want to save the wallpaper Right click on it and select "Save image as...!".