Louie Mantia, an interface designer at Apple, maintains a great iOS wallpaper directory where he likes to flex his design skills and penchant for various nerdery. He seems to have updated many of his wallpapers for the iPhone 5’s new 1136 x 640 pixel display.
Some of my favorites include Serenity, Andy’s Room (from Toy Story), Hyrule, and Don’t Panic, which looks great on an iPad’s lock screen.