It will be fascinating to learn who will choose criteria for triggering the turn on. If, for example, the criteria will be decided by a very short, obese woman with a US Marines hair cut, look for magazine cover girls, women who read the news on TV and every female fashion model in the world to be fired and replaced by those who fit the new ideal.
A better solution is to let those who have the chip implant decide criteria for being turned on. They could easily choose if their iPhone is linked to the chip's own software pull down menu. Each menu line will show different "types" of ideal types to choose from. The iPhone solution will also allow chip recipients to change their criteria "on the fly."
Hackers will inevitably pose a threat to personal iPhone control of the chip. If they can steal your password, they can also have the deciding influence on your sex life. As the sex chip becomes popular, it will not be impossibke for a hacker to try seizing control over perhaps 30 to 50 iPhone passwords at once, perhaps on a crowded metro or subway train. The resulting orgy will be hard for some metro riders to explain at home.