How can I mark an appointment as ""private" on my calendar?

Is it possible to mark appointments as private on my iPhone and iPad as I can on my PC? If so, how? This is a critical feature for most business people, and needs to be added if has not already. This is a simple feature that is very important to most users. If,it is not,possible, why? If its not available and not going to be soon,I may be forced to go back to my BB or a droid.