I was intrigued by the challenge.
Attached my attempt at emulating the esxcfg-mpath -l command.

There are some points that are not the there:
1) the PCI address of the HBA for a local disk is apparently stored in hex but displayed in decimal (I think).
My script displays the PCI address as it is stored (hex)
2) the diskname (/dev) is a name that is apparently not present in any of the SDK properties.
My script doesn't display this.

$esx = Get-VMHost -Name <esx-hostname> | Get-View
foreach($disk in $esx.Config.StorageDevice.ScsiLun){
  foreach($lun in $esx.Config.StorageDevice.MultipathInfo.Lun){
    if($disk.CanonicalName -eq $lun.Id){
	  $pathNumber = $lun.Path.Count
	  $policyName = $lun.Policy.Policy
	  $capacityMb = ($disk.Capacity.Block * $disk.Capacity.BlockSize) / 1Mb
# Disk line
	  $line = "Disk " + $disk.CanonicalName + " (" + $capacityMb + "MB) has " + $pathNumber + " paths and policy of " + $policyName
        Write-Host $line
# Path line(s)
      $preferredPath = $lun.Policy.Prefer
	  foreach($path in $lun.Path){
	    $device = $disk.CanonicalName.Substring(0,$disk.CanonicalName.IndexOf(":"))
		foreach($hba in $esx.Config.StorageDevice.HostBusAdapter){
		  if($hba.Device -eq $device){break}
		}
		if($path.Name -eq $preferredPath){$preferred = "preferred"}
		else{$preferred = ""} 
		switch($path.PathState){
		  "active" {$pathStatus = "On active"}
		  "disabled" {$pathStatus = "Off"}
		  "standby" {$pathStatus = "On"}
                 default {$pathStatus = "unknown"}
		}
		switch($path.Transport.gettype().Name){
	          "HostParallelScsiTargetTransport" {
	            $line = " Local " + $hba.Pci + " " + $path.Name + " " + $pathStatus + " " + $preferred
	          }
	          "HostInternetScsiTargetTransport" {
		    $line = " iScsi sw " + $hba.IScsiName + " <-> " + $path.Transport.IScsiName + " " + $pathStatus + " " + $preferred
		  }
	        }
		Write-Host $line
	    }
	    break
	}
  }

The script, in this format, only handles 1 ESX server at the time but it can easily be converted to a filter.

Hi guys,

One of the most useful scripts I've found is the following script to automatically Load Balance paths on an ESX server:
http://www.yellow-bricks.com/2008/04/01/load-balancing-activeactive-sans/

Is there a way to replicate this script in PowerShell that will apply to all servers in a cluster, and have it also keep the same path for LUNs across servers (i.e. If server 1 uses Path 2 to access LUN 3, Server 2 will also use Path 2 to get to LUN3)? This is important for arrays which have to transfer ownership (such as active/passive ones).

Thanks a bunch.

It's very easy to do this sort of thing with powershell. Run your script or command and pipe it to set-content and give it a filename. Or, the old redirection symbol works too, e.g. "> lun.txt".

Actually this one is hard to do because a datastore can have multiple LUNs. There is no direct relationship of VM to LUN. You can however, do VM to Datastore, and Datastore to LUN.

Mess with Get-Datastore.

PowerShell MVP, VI Toolkit forum moderator
Author of the upcoming book: Managing VMware Infrastructure with PowerShell
Co-Host, PowerScripting Podcast (http://powerscripting.net)
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As usual nice work LuCd ..any chance of exporting into HTML file ..