Well it seems my previous script was mostly "dirty", there is a problem with that script.
For the explanation of the problem see Re: Get list of available networks on an ESX host.

This should be a "working" script.

$netsystem = Get-View -id (Get-VMHost -Name <ESX-name> | Get-View).ConfigManager.NetworkSystem
$noVMnic = @{}
foreach($vnic in $netsystem.NetworkInfo.ConsoleVnic){ 
  $noVMnic[http://$vnic.Portgroup|http://$vnic.Portgroup] = $true
} 
foreach($vnic in $netsystem.NetworkInfo.Vnic){ 
  $noVMnic[http://$vnic.Portgroup|http://$vnic.Portgroup] = $true
} 
 
foreach($pg in $netsystem.NetworkInfo.Portgroup){ 
  if(! $noVMnic.ContainsKey($pg.Spec.Name)){
    Write-Host $pg.Spec.VswitchName $pg.Spec.Name "Virtual Machine Port Group"
  }
  else{
    Write-Host $pg.Spec.VswitchName $pg.Spec.Name $pg.Port[0].Type
  }
} 
 

Since the forum SW seems to have problems with square brackets I attached the script.