> Is it sort of like a try/catch for error events?

Yes, but it's also sort of like a try/catch for thrown errors.

    d = domain.create()
    d.on('error', function(e) {
      console.error('an error: ', e)
    });
    d.run(function() {
      throw new Error("whoops")
    })

would console.log, rather than crashing the program.

When an EventEmitter is bound to a domain, their error events and any errors thrown while emitting an event on them will be handled by the domain object that they're bound to.