I still don't know why it stopped working or what the fix actually does, but it worked for me. My iSight stopped working, but not completely and the last thing I did was to have Parallels use my iSight (which prompted for drivers I didn't install but worked anyhow), and then giving it back to my Mac and it continued to work, until I awoke my mbp from sleep the next time. I tried all the usual (annoyingly lazy) fixes, reboot, smc reset, and so on... everything short of reinstalling a combo-update or just reinstalling my mac. Those sure are popular "fixes". But I digress.
It turned out then whenever I plugged in *any* usb device, my iSight would stop working, which sucks when you rely on a usb stick occasionally to connect to the internet. But enough talk, the fix that worked for me is here, good luck with it.