I don't like something that covers what I'm trying to read (ref. zerojay's posting, which I agree with), and I wouldn't like the screen to dim, for the same reason. Even if the device is busy there might be something I'm trying to read there. This is even a problem with the older devices, with those little pop-ups (loading, searching, etc) which covers something I'm currently reading.

So, whatever solution anyone comes up with, please don't let it interfer with/cover up other useful stuff/info on the screen.