We originally had build 9.0.3042 installed on a cluster environment and were able to create maintenance plans. Integration service was installed and we were able to view the maintenance plans in Integration Services and were able to export the plans.
When we ran KB921896 to upgrade the build to 9.0.3054 we lost the ability to view the maintenance plans within SQL Server >> Management >> Maintenance Plans. We attempted to build a new plan. The wizard appeared. It created the plan showing the new jobs but the plan still did not show within SQL Server. Thus we were unable to modify the plan. It did show within the Integrations Services area and we were able to export the plan to a dtsx file.
The only way to remove the jobs was to delete the records found in msdb.sysmaintplan_subplans first.