See what the arrow is pointing to? I have a hard shell for my 9860 and it not only has openings for the camera and the flash but also has another small opening for that thing that sits in between. It seems to me that this opening in between needs to be uncovered for some reason. Is that a sensor of some type? A microphone? Speaker? Can someone here enlighten us?
Actually my guess is that it's a mic, for when you're taking video. So instead of picking up sound from your phone's mic located at the bottom, the mic is directional to what you're filming.
I don't know if it's the speaker. If you look through the help books (or whatever they're called) that came with the phone, nothing points out what this is.