There are some colored trackballs available on cnn.cn, but I don't know about illuminated... by the way, in order to change out the trackball you will void your warranty... the only way to get to the trackball is to take the entire thing apart and get to the trackball from behind.
No because unlike the bold, your trackball assemby is set to only illuminate the ring around the trackball right? I say you guys should be happy. The trackball's get dirty and so even white trackballs look yellow after a while. Most Bold owners black their trackballs, and you guys get a black one from the get-go with a cool ring around it.
As for whether or not you can illuminate your trackball, no. Only if you mod your device and use a custom trackball assembly etc...