While some love to hate the linen textures that are so prevalent in Lion, I'm kind of into them. I use the dark linen texture as my Mac wallpaper and wanted the same look on my iOS devices. iOS 5 actually uses linen textures for various interface elements (including Notification Center's background), but oddly, it's not offered as an option for the lock and home screens.
Fortunately, Lion includes swatches for dark and light versions of the texture, which you can find here:
iOS won't let you tile wallpapers, and so I used the swatches to create native-resolution images for both the iPhone and the iPad.