It's the strangest thing - the phone *has* backlit buttons (I was convinced it did not) but they're only active at certain times - and pressing them isn't one of them. If you're in a call, the buttons are lit up but most of the time you're using the phone and not on a call, the buttons are dark. I was using the phone in a dark room and the screen would light up (setting my alarm) but the hard keys were not lit. For the entire time I'm on a voice call, however (speakerphone) the buttons were lit up.
Don't have a comprehensive list of times the buttons are lit/dark but I do find it odd that they don't automatically come on when the screen lights up...