I use the following as a hack.  I will replace this when the Seam API changes.  I believe there is a JIRA for this, but I am not sure.

import java.lang.reflect.Field;
import org.jboss.seam.async.QuartzTriggerHandle;

public class QuartzUtil {

     public static String getTriggerName(QuartzTriggerHandle handle)
     {
          Field field;
          String value = null;
          try {
               field = handle.getClass().getDeclaredField("triggerName");
               field.setAccessible(true);
               value = (String) field.get(handle);
          } catch (SecurityException e) {
               e.printStackTrace();
          } catch (NoSuchFieldException e) {
               e.printStackTrace();
          } catch (IllegalArgumentException e) {
               e.printStackTrace();
          } catch (IllegalAccessException e) {
               e.printStackTrace();
          }
          return value;
     }
}

I do not.  When you find it please post it here.