Hey just got done making a quick YouTube Video on how you can remove the dust from behind the plastic lens cover on your Curve. This was driving me crazy and I've seen this on multiple devices. Unfortunately my carrier wont do anything about it so I did.
If using a screwdriver use the smallest one you can to pry it open. I used a fingernail. If you have lots of dust under the cover chances are the adhesive used to secure it is loosening up so it should come up fairly easy. Take your time and pry it slowly. Don't yank on it.
Check out the video! YouTube - How To Remove Dust From Under Your BlackBerry Curve