Download the Official Set of New iPhone OS 4.0 Wallpapers
The latest Beta 4 of iPhone OS 4.0 packs 25 new non-distracting wallpapers which goes really well with the new “Homescreen Wallpaper” feature in OS 4. If you don’t have access to iPhone 4.0 Beta and want to have these on your iPhone, simply download them and follow the instructions below to sync it with your iPhone and iPod touch.
Correct me if I am wrong but this is probably the first time Apple has updated the stock wallpapers back from iPhone 1.x days.
To transfer these to your current iPhone OS 3.x firmware on iPhone/iPod touch, simply select this new “Wallpapers” folder in iTunes to sync with your iPhone and then select “Use as Wallpaper” option to set it as wallpaper.
If you want to use these as your homescreen wallpaper on iPhone OS 3.x then you will have to first jailbreak your iPhone using Spirit and install Winterboard app from Cydia. Instructions for jailbreaking iPhone can be found here, and instructions on installing Winterboard from Cydia can be found here.