Scott Craig [2000 4.7L - Nashville, TN]
durango@craigcentral.com
When you are making a turn the suspension (and bearings, rotors, etc.) have some side load on them instead of just the normal up/down load. You can frequently hear suspension noises when turning that don't show up when you are going straight. Also, at speed noises like brakes and bearings can reach a frequency high enough that they can't be heard, but at slow speed they are easily noticeable.
My guess is a slightly warped brake rotor. I say that because mine makes a similar noise and I know it's because the left front rotor is slightly warped.
A warped brake rotor will "Chirp" sometimes as the warped area goes between the pads. I know, mine does! The rotor doesn't turn smoothly between the pads, it rubs on one side or another and forces the caliper to move constantly. If the caliper slide pins don't have enough lubricant on them, and that constant movement will wear it off quicker, lubricating them may help for a while.