This is a custom-developed cmdlet from velemental.com. This can be referenced as part of your Powershell profile, or just included at the top of your script. http://velemental.com/2012/03/29/managing-metadata-in-vcd-with-powercli/

Get-CIMetadata.ps1

Function Get-CIMetaData {
	<#
	.SYNOPSIS
		Retrieves all Metadata Key/Value pairs.

	.DESCRIPTION
		Retrieves all custom Metadata Key/Value pairs on a specified vCloud object

	.PARAMETER  CIObject
		The object on which to retrieve the Metadata.

	.PARAMETER  Key
		The key to retrieve.

	.EXAMPLE
		PS C:\> Get-CIMetadata -CIObject (Get-Org Org1)
	#>

	param(
		[parameter(Mandatory=$true,ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)]
		[PSObject[]]$CIObject,
		$Key
	)

	Process {
		Foreach ($Object in $CIObject) {
			If ($Key) {
				($Object.ExtensionData.GetMetadata()).MetadataEntry | Where {$_.Key -eq $key } | Select @{N="CIObject";E={$Object.Name}}, Key, Value
			} Else {
				($Object.ExtensionData.GetMetadata()).MetadataEntry | Select @{N="CIObject";E={$Object.Name}}, Key, Value
			}
		}
	}
}