Technical limitations? Put down the kool aid. We've had custom wallpaper on our JB phones for years now without any performance hit to speak of. Get a clue.
LOL get a clue youself. As many have written here many times it is different. Cydia implementation si simple images, Apple's one isn't so it is slower on these devices. We know how apple works you can love it or hate it: if a thing is not running good and speedy, they usually don't implement it. Check a video on 3GS or a video with an app from iphone 3G... GIGANTIC difference. This is why Apple doesn't implemented video in 3G. Same thing here... but especialy i can't understand why some ppl are nuts about backgroung lol.