score:5
When I first read your question, I thought you might be referencing mobile-checkin, which is starting to become popular. As I looked into your question, I think this is just fancy wording for the ability to show your email at a checkin counter, where they will pull up your info and print your boarding pass.
Taken from wikipedia electronic ticket:
To check in for a flight with an e-ticket, the passenger usually goes to the check-in counter in the usual manner. There they may be required to present some personal identification, a credit card or the e-ticket itinerary receipt. Theoretically it is not even necessary to present the e-ticket itinerary receipt document or quote the confirmation code or e-ticket number as the reservation is confirmed solely on the basis of the passenger's identity, which may be proven by a passport or the matching credit card. However, producing a print-out of the itinerary receipt is required to enter the terminal of some airports as well as to satisfy immigration regulations in most countries.
At the check-in counter, the passenger checks-in his/her luggage and receives a boarding pass. However, electronic ticketing allows various enhancements to checking-in.
If your ticket does give you a barcode with a seat number (like below), then you can use this as your actual boarding pass. TSA and the gate attendants just ask to place your mobile device on their scanner. I typically use this for domestic flights in the states, but I haven't seen this for international flights from the US.