Derek Melber has a very good analysis/summary of the PowerShell security over at WindowsSecurity.Com. If you run across someone concerned about the security aspects of PowerShell, this would be a good article to point them to. The article is HERE.
Jeffrey Snover [MSFT]
Windows Management Partner Architect
Visit the Windows PowerShell Team blog at: http://blogs.msdn.com/PowerShell
Visit the Windows PowerShell ScriptCenter at: http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx