Setting up the system to unlock all doors when you place your hand by one of the front door handle with the FOB present: http://www.toyotaiguide.com/iGuide_Camry.htm

Select your car.

See KEYS AND DOORS, then SMART KEY / REMOTE KEYLESS ENTRY FUNCITON, then Program Door Unlocking. Or, see page 40ish of the manual.

UPDATE:

After some more research:

"Auto Lock Delay" is set to either 30 or 60 seconds and there is no way to turn it off. "This function regulates the interfval between unlocking and automatic relocking of doors." It works but we really want is to have the car lock automatically when it was previously unlocked -- which seems to be the problem above. Not lock automatically if it was previously locked and the doors were no opened.

(The following is the setting that do the same as the above reference iGuide when it comes to using the handle but with the FOB button.)
"Unlock / 2 oper" is set to ON and it can be set to off. "This function unlocks the driver's door when the UNLOCK switch is pressed once, and unlocks all doors when pressed twice within 3 seconds. If set to OFF, pressing UNLOCK once unlocks all door."

Customizable features (PDF)