Metrolink has started operating on a new schedule today. While the Riverside, 91 and weekday San Bernardino Lines have not seen any changes, the IE-OC and OC Line trains all have at least one minor schedule adjustment. Also, weekend San Bernardino service has changed. Most notably, Riverside-Downtown will now see late-night weekend service, with a train leaving Los Angeles at 9pm and returning here at 11:15pm. Also, the IE-OC Line will revert to its previously-used once daily weekend schedule.
All the details are available on Metrolink's web site.
RTA CommuterLink routes that connect to Metrolink trains- 206, 208, 210 and 212- have also changed schedules in order to continue connecting with the trains. The new schedules are available from RTA. (PDF)