Chinese language site Livesino.net (somehow the sites that get the good leaks tend to be Chinese, Russian or Vietnamese, and I am not quite sure why) depicted how the People app is on the business end of a user interface makeover, where clicking on a contact’s first letter will change the look of the filter. Apart from that, it seems that a search box inside the updated People app will be part of the make up, while the contact page for each profile has also been revamped.
As for the Calendar app, not much changes are expected in the user interface, although it is tipped to arrive with a “What’s Next” feature which will let you see the next series of events on the calendar itself.