SELECT 'IsClustered', SERVERPROPERTY('IsClustered')

     Jul 13  

Sometimes this is me

               bool isClustered = false;

                ManagementObjectSearcher searcher = new ManagementObjectSearcher(
                                    new ManagementScope(string.Format("\\\\{0}\\root\\cimv2", machineName))
                                   , new ObjectQuery("SELECT PartComponent FROM Win32_SystemServices"));

                foreach (ManagementObject iQueryObj in searcher.Get())
                {
                    string name = iQueryObj["PartComponent"].ToString();
                    if (name.Contains("ClusSvc"))
                    {
                        isClustered = true;
                    }
                }