The primary purpose of this operation is for an administrator to list all timer jobs in the SSP especially if a computer had Microsoft Project Server installed, and then was uninstalled. In this scenario, the Project Server SSP timer jobs still exist in the SSP database even though Project Server is not installed on the computer. To delete these orphan timer jobs, use the Deletessptimerjob operation. For more information about timer jobs, see the Remarks section of this article.
If a SharePoint solution deployment fails, yet the timer job is created and not running, you will be unable to redeploy or retract the solution. The retract / deploy buttons will not be present in Central Admin and stsadm will declare that a "deployment or retraction is already under way for the solution". You can find yourself in this state if the “Windows SharePoint Services Administration” service is stopped when you first attempt to deploy, but even after you realise your mistake and start that service, the solution deployment is still stuck. The answer is hidden in that long list of stsadm operations: