Just picked up my Dark Charcoal Hemi this past Friday and noticed this same sound a few times. Seems to be most prevalent around 25-30 MPH. FWIW, I have Quadra-Lift and Quadra-Drive II with the 20" wheels.
I was just browsing over at wk2jeeps.com and saw the following info
at the bottom of the page that shows the TSB's.
Electronic Stability Control (ESC) Clicking Noise
The driver may notice a clicking sound coming from the front or underneath the vehicle. This occurs when the vehicle is traveling above 35 mph and during the first portion of a drive cycle. The ESC system will run a calibration routine and if the driver lifts off of the gas pedal, the ESC system will stop the test because the drive may need to brake. The clicking sound is the valves in the ESC system. Once the calibration routine is successful, the noise will not return until the next ignition cycle. Once the ESC system has learned 50 times, the calibration will not be run during every ignition cycle. The sound may also become less noticeable over time. This sound is normal and no service needs to be done.
Do you all suppose this is related to the "playing card" noise we're hearing? Has anyone with the noise noticed that it occurs less often after owning the vehicle for a while, or is it just as common?