Default to Powershell in Windows Core
One of the big pushes in Server 2012 is the use a Server Core installation instead of the full GUI install. Microsoft have put a lot of effort into encouraging administrators to use Powershell as a core tool for day to day administration of servers, which is why is seems a bit strange that a Server Core installation boots to a traditional command prompt instead of a Powershell prompt.
To change your Server Core installation to launch Powershell instead of the normal Command Prompt is a simple registry change.
From the Command Prompt run Regedit
Navigate to HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
The highlighted Shell dword is what we need to change, so double click on that and type in powershell.exe
Click Ok and close the Registry Editior.
When you reboot the server you will now have a Powershell prompt.