Replace quick launch camera button?

[tuan time]

During the keynote, they were talking about how you can double click the homebutton and launch a camera button. Now how difficult would it be to replace the camera button with any button of your choosing i.e. messaging or facebook?

 

[Centsy]

Wouldn't be surprised if a jailbreak app came out to do this. But it wouldn't be until after iOS5 is released... Also, you can use Activator to do something similar right now.