hi guys
Since I've owned the car I've noticed a "rattling" sound emanating from the top of motor (cam cover) area very similar to this sound (not my car):
http://www.youtube.com/watch?v=LCbScUfDPhI
Mine seems to be pretty much quiet at idle compared to the video but maybe between 1300-1500 rpm it'll be very noticeable.  
 
Any ideas?? someone mentioned "idler bearing on timing belt" maybe?
 
Cheers

hi Josh, most sounds are not from where you think they are! if the sound is at a certain rpm I would check the exhaust bolts, flanges etc as they might be vibrating if loose

hey pat !
I think you may be right, I have a funny feeling it's from the turbo manifold studs/bolts or something related to that which is resonating. Will need to investigate further I think maybe with one of those mech stethoscopes.   
Cheers mate

I had a similar noise in my 3sgte a few weeks ago sounded like it was at the top of the motor but it was the bolts on the dump pipe to collector flange they where all loose

So now the noise seems to have pretty much gone away on its own lol
 

A good result in the end haha. Maybe the item that was rattling may no longer be connected, could be a good thing. Scheduled Weight Reduction brought to you by Toyota hahaha.