Adding an appointment to your calendar with Siri in iOS 6 is really easy. Just ask Siri to “Add an appointment to Review Budget Tomorrow at 12pm”. Siri will create a new calendar event titled “Review Budget” and will schedule it for tomorrow at 12pm.
You can take this a step further by asking Siri to schedule the meeting with someone who is in your contact list. By doing this, Siri will create the calendar appointment and then automatically send out an invite for the appointment to the person you scheduled the appointment with (as long as you have an email address listed with that contact). For example, ask Siri, “Add an appointment to Review Budget tomorrow at 12pm with Joe Smith.” Insert any name from your contact list in place of “Joe Smith.” Siri will create the appointment, add Joe to that appointment, and then send out an email calendar invite to Joe asking for him to respond to the appointment. As soon as he responds, a little green check mark appears in your calendar event on your iPhone, iPad (Mini), iPod Touch, or your Mac.