Index: src/main/java/info/magnolia/module/scheduler/StatefulCommandJob.java
===================================================================
--- src/main/java/info/magnolia/module/scheduler/StatefulCommandJob.java	(revision 0)
+++ src/main/java/info/magnolia/module/scheduler/StatefulCommandJob.java	(revision 0)
@@ -0,0 +1,47 @@
+/**
+ * This file Copyright (c) 2010 Magnolia International
+ * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
+ *
+ *
+ * This file is dual-licensed under both the Magnolia
+ * Network Agreement and the GNU General Public License.
+ * You may elect to use one or the other of these licenses.
+ *
+ * This file is distributed in the hope that it will be
+ * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
+ * implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
+ * Redistribution, except as permitted by whichever of the GPL
+ * or MNA you select, is prohibited.
+ *
+ * 1. For the GPL license (GPL), you can redistribute and/or
+ * modify this file under the terms of the GNU General
+ * Public License, Version 3, as published by the Free Software
+ * Foundation.  You should have received a copy of the GNU
+ * General Public License, Version 3 along with this program;
+ * if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * 2. For the Magnolia Network Agreement (MNA), this file
+ * and the accompanying materials are made available under the
+ * terms of the MNA which accompanies this distribution, and
+ * is available at http://www.magnolia-cms.com/mna.html
+ *
+ * Any modifications to this file must keep this entire header
+ * intact.
+ *
+ */
+package info.magnolia.module.scheduler;
+
+import org.quartz.StatefulJob;
+
+/**
+ * A simple subclass of {@link CommandJob} which implements the {@link StatefulJob} marker interface,
+ * allowing the non-concurrent execution of jobs.
+ *
+ * @author gjoseph
+ * @version $Revision: $ ($Author: $)
+ */
+public class StatefulCommandJob extends CommandJob implements StatefulJob {
+
+}
Index: src/main/java/info/magnolia/module/scheduler/JobDefinition.java
===================================================================
--- src/main/java/info/magnolia/module/scheduler/JobDefinition.java	(revision 40600)
+++ src/main/java/info/magnolia/module/scheduler/JobDefinition.java	(working copy)
@@ -53,6 +53,8 @@
 
     private String catalog;
 
+    private boolean isConcurrent = true;
+
     private Map params;
 
     public JobDefinition() {
@@ -107,6 +109,14 @@
         this.cron = cron;
     }
 
+    public boolean isConcurrent() {
+        return isConcurrent;
+    }
+
+    public void setConcurrent(boolean concurrent) {
+        isConcurrent = concurrent;
+    }
+
     public Map getParams() {
         return this.params;
     }
Index: src/main/java/info/magnolia/module/scheduler/SchedulerModule.java
===================================================================
--- src/main/java/info/magnolia/module/scheduler/SchedulerModule.java	(revision 40601)
+++ src/main/java/info/magnolia/module/scheduler/SchedulerModule.java	(working copy)
@@ -173,7 +173,8 @@
             return;
         }
 
-        JobDetail jd = new JobDetail(job.getName(), SchedulerConsts.SCHEDULER_GROUP_NAME, CommandJob.class);
+        final Class jobClass = job.isConcurrent() ? CommandJob.class : StatefulCommandJob.class;
+        final JobDetail jd = new JobDetail(job.getName(), SchedulerConsts.SCHEDULER_GROUP_NAME, jobClass);
         jd.getJobDataMap().put(SchedulerConsts.CONFIG_JOB_COMMAND, job.getCommand());
         jd.getJobDataMap().put(SchedulerConsts.CONFIG_JOB_COMMAND_CATALOG, job.getCatalog());
         jd.getJobDataMap().put(SchedulerConsts.CONFIG_JOB_PARAMS, job.getParams());