In order to use Windows PowerShell for SharePoint 2010 Products, a user must be a member of the
SharePoint_Shell_Access role on the configuration database and a member of the
WSS_ADMIN_WPG local group on the computer where SharePoint 2010 Products is installed. However, the result of running this cmdlet is that the user specified with the
UserName parameter will have the dbo_owner role access on the affected databases as described above. Therefore, you should carefully plan which users are given this access.
From: http://technet.microsoft.com/en-us/library/ff607596.aspx
Wahid Saleemi Sr. Consultant, Avanade http://www.wahidsaleemi.com