Hi,
I have been struggling against this problem for a long time. I had the same kind of issues your all have, I tried resetting PRAM and so on, deleting preference files, installing patches like the published in coriam, etc. and no matter how hard I tried, I always had the i-sight and bluetooth working on intermitenly. At the end, I decided to open up my MB (I did it once when I broke the display). With the laptop opened I find out that applying some kind of presure through the conector of the display to the motherboard the problem reproduced all of a sudden. It seemed that due to short circuit. So I disconnected that cable, cleaned it, and reconnect again making sure no other thing is stressing. Finally, I restarted my system withouth any kind of PRAM, safe mode, etc. and voilà! it worked, and it is keeping working since then....
So, if you dare, and you Mac is out of warranty period, try to open it (only the back cover, not needed to dissamble the display) and after making sure the cable is ok, with the lid open, restart your system and see what happens digging in.
Caution: don't touch the motherboard or your OS will freeze, and you will have to restart again.
I hope this helps,