If anyone has experienced a problem with a rattle in their intake manifold you are not alone. This a factory defect in manufacturing and Toyota is totally dropping the ball on this one.
There is a bulletin, but it's for a limited time, either 36k,50k,or who knows.
When you take your car to the dealer the service writers try to act like they don't know what it is, and if you're not aware of the bulletin they will try to charge you between $600 and $800 to fix it.
Although they say it does not cause problems(we don't know for sure and they aren't telling) it sounds like your car is about to throw a rod.
This effectively renders the car not saleable on the used market, as no one in their right mind would buy a car that sounds like the engine is going to blow up any moment.
If you own one of these vehicles, rest assured you will have the problem, which typically starts at about 50 to 60 thousand miles, as the baffle inside the manifold becomes loose and sets a up a vibration/vortex and can't be fixed as it's inside near the number one cylinder.
So, buyers beware, Toyota is giving you the royal shaft on this one.
If you own a Camry and it has less than 50 K miles proceed immediately to your Toyota Dealership and have it replaced, it's only a matter of time until it will happen to your car.
Here is a link to Toyota Motor Sales USA to complain if they give you any run around about fixing it.
http://www.toyota.com/help/contactus.html