In iOS 4.0 if you receive an email that says tomorrow night Apple has now made it easy as pie to create an event for that tomorrow night engagement. I am guessing that a tomorrow afternoon or tomorrow morning will result in the same prompt. When clicking on the actionable link, a popup titled Create Event appears. This results in a calendar entry for the next night beginning at 8:00pm. Its the small things like this that make Apple products stand out from the pack.