They said they thought something was binding in the steering system, similar to previous gen Camrys, even though the '07 have a completely different system (electronic). They ordered a "new steering column" and I did notice during the repair that it appears that is what they did. Fortunately my issue was very replicable so they saw it themselves. My issue was originally intermittent and got more and more frequent to the point where it happened at will. I noticed in the earlier stages that loading the front suspension seemed to make it easier to get the clicking. You might try going in a parking lot and turning the wheel harder than you normally would at 20-30mph. Also, being on a steep downhill and/or moderate braking while turning should also load up the suspension. I first noticed my issue in my work parking garage where the ramps are steep and require 180 degree switchbacks.

My dealer said the issue is not a safety threat and if your car is like mine, it will get more frequent, which will help in showing it to the dealer. I will see if I can obtain more details and/or a service ticket number. I don't know if Toyota's service tickets are visible nationwide--I know from previous experience many other car makers' are. BTW, my car had about 5,000 miles when it first started.