Now you can change your wallpaper for you homescreen (not lockscreen) by installing the application called "Summerboard".

Here's how to do it:

^Go into installer and scroll down to themes and download one.

^Go into "smbprefs" and switch theme to the one you have recently downloaded.

^Go back into installer and uninstall that theme.

^You can use the pictures and set them as your background for your iPhone and iPod.