For everyone with jailbroken iPhones there's a new Winterboard theme you can download via Cydia that will change your wallpaper and battery screen to images of the Si. The speedometer actually indicates your battery life while charging. The Honda logo at the bottom is the image you slide to the right to go to the home screen. Here are some screen shots.
Wallpaper while not charging:
Wallpaper while charging:
You can have the same background image without jailbreaking your iPhone if you can find a copy of the image. I believe the battery wallpaper can only be achieved by jailbreaking. You must also have Winterboard installed (a jailbroken app).