Many people updated their 2nd Generation iPod Touches and their iPhone 3G (not 3GS) in hopes that they could get homescreen wallpapers on it, only to find out that homescreen wallpapers cannot be set in those iPod models. Then they find out in horror that they can’t downgrade iOS 4.1 to back to 3.1.3 (unless you were able to make a backup copy of your SHSH blobs) so they can jailbreak 3.1.3 to add homescreen wallpaper functionally. But fortunately there will be a jailbreak tool for iOS 4.1 called “Greenpois0n” available any day now. For iOS 4.1 users, there IS hope that you can have homescreen wallpapers, multitasking (i wouldn’t recommend multitasking on those old iPod models.) and adding themes to iOS 4.1. But in the mean time, be patient.
Note: Don’t EVER update iOS because theres a chance that apple is releasing another version just to prevent another jailbreak