Check this
http://blogs.msdn.com/crm/archive/2009/06/24/microsoft-dynamics-crm-4-0-iworkflowcontext-interface.aspxThe Workflow Expansion Task plugin executes asynchronously for a particular message in CRM. For example if you have published a workflow to execute on Create of account, the Workflow Expansion Task plugin will be registered as a step on the Create message for the account entity when the workflow is published. The step will execute asynchronously. The Workflow Expansion Task plugin will retrieve all workflow rules that are published and that are configured to execute when the current message executes. So if you have more than one workflow that is published and should execute on the create message, the primary entity for the workflow is account, and you have access to the workflow based on the scope setting, those workflows will be retrieved.
