审批工作流
http://office.microsoft.com/zh-cn/sharepoint-designer-help/HA010100587.aspx
http://office.microsoft.com/zh-cn/sharepoint-server-help/HA010154425.aspx
http://office.microsoft.com/zh-cn/sharepoint-server-help/HA010154429.aspx
http://technet.microsoft.com/zh-cn/library/ee704556.aspx
http://msdn.microsoft.com/zh-cn/library/ee231606.aspx