Hi, I had the same exact issue with the camera and leak 2. I just fixed mine, here's what I did. Maybe it will work for you.
Push the CameraGoogle.apk from the FIRST 2.2 leak to SD card
in ADB shell with SU and /system mounted RW
rm /system/app/CameraGoogle.apk
rm /data/dalvik-cache/system@app@CameraGoogle.apk@classes.dex
rm -r /data/data/com.google.android.camera
busybox install /sdcard/CameraGoogle.apk /system/app
Reboot
After that, camera works fine (for now)...hope this helps.
Ned
I have tried this too, several times with different roms. On the last go round I found something that might give a clue to whats happening. I would take a picture of the blank screen, I tapped the picture to view it. When viewing it in the gallery I clicked the menu button that shows the Camera in the top right. When I went back to the camera it had a picture that looked like infra red. It would change as I moved the camera around, I could see in the background what should be showing in a normal viewfinder. See attached.