If you have key tones set to "no" this may or may not work (does on my 8100)
Call your voicemail through your speed dial, pressing the speed dial buttons doesn't make a sound (with the keytones off as I said before). Turn your sound down (if your trying to be sneaky sneaky) then go and enable your camera. Your phone stays in the call, and then there's no out loud sound for the camera!
A few people have tried to just tweak the coding on the OS and delete the sound, but that's ended up with losing all functionality of the camera
Other than this, and the headset option, there's no other way... Guess they don't want us taking pictures of our drinks during meetings
I like how so many of these topics have popped up recently! I was going to copy and paste this into the other one, but ehhhh I don't care enough