CredSSP

http://blogs.technet.com/b/heyscriptingguy/archive/2012/11/14/enable-powershell-quot-second-hop-quot-functionality-with-credssp.aspx

Back in the Windows Vista days, we introduced a new security delegation module called Credential Security Service Provider (CredSSP). This was originally designed to work with Terminal Services because everything in Terminal Services is basically a second hop.

Also:

http://blogs.msdn.com/b/powershell/archive/2009/11/23/you-don-t-have-to-be-an-administrator-to-run-remote-powershell-commands.aspx