Ah. There isn't a way that I've found. I read that it's the same for some Sprint phones, where they see it as a privacy thing. They don't want you taking pictures of people without their knowing about it (or something like that) and so they make it so you can't turn off the click sound without muting the entire phone. I just tried that and it does stop the shutter sound. Third part camera apps don't seem to have the same concern.
Found this hack on another site.
If you're rooted, install Root Explorer, navigate to /system/csc (make sure r/w is toggled, long press "feature.xml" and open in text editor). Scroll down to <Camera> then to <CscFeature_CameraShutterSoundMenu>false</ Edit the setting false to true.
Save, reboot, then you will have the option to disable the shutter sound.