For users who updated their iOS devices to 6.1 yesterday Fandango is now the commerce partner for movie ticket sales via Siri. If you look up movies using Siri you get the Rotten Tomatoes powered list with an option to buy using Fandango. If you don't have the Fandango app on your device you'll be prompted to install it to complete the transaction.
Fandango has reported that mobile now accounts for more than 30% of ticket sales. That will undoubtedly increase with Siri and iOS integration.
There are many Siri critics out there but the process of looking up a movie and (now) buying a ticket is pretty compelling. In fact this may well become the primary way that many iOS users buy movie tickets in the future. Once a credit card is on file with Fandango it's going to be faster and easier than conducting the same transaction even on the PC.
In addition, there's Apple Passbook integration post purchase.
This is yet another "mobile payments" point solution (it's really e-commerce on a mobile device) that will get people comfortable with the idea of using their phones to conduct transactions and pay for things. The convenience and value here are obvious to consumers.