Impersonation steps are new to SharePoint Designer 2010. Using impersonation, you are able to perform steps as the author of the workflow. The author is always the person who published the workflow to SharePoint and not the person who created an instance of the workflow. This is especially important when dealing with impersonation.
You can perform the following actions as part of an impersonation step. All except the last action are only available as part of an impersonation step:
• Set content approval status
• Create items
• Update items
• Delete items
• Add, remove, and update item permissions
When considering implementing impersonation steps you need to consider who is going to publish the workflow ...