There were several JMRI clinics at 2012 NMRA convention in Grand Rapids, including both old favorites and several new ones.
Slides:
David Duchamp's clinic on "Running Trains with JMRI's Dispatcher"
David Duchamp's clinic on "Using JMRI with C/MRI Hardware"
More information on the convention can be found on the convention website. Many interesting clinics are listed in addition to the ones listed here, including two on CATS.