Towing requires torque. I'm guessing the electric motor in the Camry does not have that much torque, so Toyota didn't want to take a chance that towing would damage the drivetrain, so they put that warning in the manual for warranty purposes. I'm sure that the car is fully capable of towing very light loads (i.e. bike racks or even small trailers) but that doesn't mean that Toyota wants to actually state that officially.

CAMRHEE Hybrid - FOR SALE!!!!
Completed Mods: RK-Sport body kit, 18" LexusGS430 wheels 235/50ZR18 tires, TRD/SE springs, Rear Lip Spoiler, Terk XM-Direct, Smoked tail lights, Sliding Armrest, Rear Bumper Applique, Front License Bracket, Lower Grill chrome inserts, K&N, Blaupunkt THB200A sub, moved rear HSD emblem
Future Mods: fog lights, black chrome my wheels

http://www.greenhybrid.com/share/fil...fterFront4.JPG