I would assume a boob job... and I can assure you, that I didn't notice anything out of the ordinary. Two years ago, when she was clinging to Greg Norman, I chatted with her for several minutes at the Shell Houston Open. She followed Norman's group just like every other spectator.
A little tid-bit off topic.... Greg Norman looks like he weighs 130 lbs. I'm 5'11 and 165 lbs... and I swear, that guy was MUCH smaller than me. He's rail thin.