I had to install the August 2010 CU to fix another issue (which it did actually resolve). Unfortunately, it just broke something else.
After installing the August 2010 Cumulative Update for SharePoint 2010, the User Profile service may stop working. You will see the following event in the the Application event log, with Event ID 3:
Source: Forefront Identity Manager
Microsoft.ResourceManagement.Workflow.Hosting.WorkflowManagerException: Forefront Identity Management Service does not support workflows of type ‘Microsoft.ResourceManagement.Workflow.Activities.SequentialWorkflow, Microsoft.ResourceManagement, Version=4.0.2450.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35’. Continue reading User Profile Service Problem After Installing SharePoint 2010 Update