Determine if powershell runs within a virtual machine.

isVM.ps1

function isVM{
  (gwmi win32_bios).version -match "vrtual"  
}


or (from http://www.windowsnetworking.com/kbase/WindowsTips/Windows7/AdminTips/VirtualPlatforms/UsingPowerShelltodeterminewhetherWindowsisrunninginavirtualmachine.html)
Function isVM {

$objWMI = Get-WmiObject Win32_BaseBoard

$bln = ($objWMI.Manufacturer.Tolower() -match 'microsoft') -or ($objWMI.Manufacturer.Tolower() -match 'vmware')

return $bln}