At a press event this morning, Los Angeles Mayor Eric Garcetti announced the new LA Mobile app that allows DASH and Commuter Express transit riders to use a smartphone to pay fares. The app is a collaboration between city of Los Angeles Department of Transportation (LADOT) and Portland-based technology company GlobeSherpa, which is also piloting an SF Muni transit fare app later this year. Similar fare apps are already live in New Jersey, Boston, and Austin, and on some commuter rail systems.
For now, the LADOT app is planned for a one-year demonstration, with the long-term future of pay-by-phone technology unclear.

The LA Mobile app requires that users set up a credit card account, then pay for fares on a per-boarding or monthly-pass basis. (Clarification: No single trip payment; users need to purchase 20-trips minimum.) Validation is performed via an animated screen shown to the driver while boarding.
The pay-by-phone app is available only for LADOT-operated transit: DASH and Commuter Express. These are by no means the workhorse systems for transit in the city of Los Angeles; that would be Metro's bus fleet with 400+ million annual boardings compared to LADOT's 2.5+ million (data from 2004-05). Nonetheless, LADOT transit ridership represents an important "sandbox" to work out any system kinks before wider implementation.
LA Mobile appears a little more complicated than just paying by tapping the phone to the fare box, available in Asia and given mention in Metro's long-long-term app plans. Virtual ticketing is still a significant step forward. It could lay the basis for later upgraded convenience.
SBLA has not tried the LA Mobile app yet. How about you, readers? How is it working on your LADOT commute? Any glitches or rough edges in need of improvement?
For additional details, see GlobeSherpa article or Mayor Garcetti's Press Release.