Ask GMail: Please read my airfare receipts and make calendar events

TripIt does this by reading all your emails if you have the settings properly set up. It also classifies your eventbrite and meetups into calendar events.

Google Now does this. Also with packages, etc. It is quite nice. So the infrastructure is there...somewhere...

https://www.google.com/experimental/gmailfieldtrial

What you're suggesting is probably phase 2.