Stay on schedule with a full calendar view of your weekly plans. First enter the built-in iPhone calendar app in portrait mode. When you see the monthly view, tilt the phone into landscape mode. The monthly view will transform into a detailed display of your scheduled events for the week. The events are color-coded according to work/home, etc. (Again, remember to unlock portrait mode before using this feature.)
Also see :- 10 Hidden iPhone Tips, Tricks [Part 3]