SharePoint: delete files in batch

###################### DELETE FILES IN BATCH
$w = Get-Spweb http://win2008r2sp2010.w2k8.dev/pressclippings
$list =  $w.Lists.TryGetList("Documents")
$query = New-Object Microsoft.SharePoint.SPQuery;
$query.ViewAttributes = "Scope='Recursive'";
$query.RowLimit = 1000;
$cmdFormat = "  <Method ID=`"Del{0}`">
    <SetList Scope=`"Request`">"  + $list.ID + "</SetList>`
    <SetVar Name=`"Cmd`">Delete</SetVar>`
    <SetVar Name=`"ID`">{0}</SetVar>`
    <SetVar Name=`"owsfileref`">{1}</SetVar>
  </Method>`r`n"
$len = 0;
do {
    $listItems = $list.GetItems($query)
    $len = $listItems.Count
    if($len -gt 0){
        $cmdString = "<?xml version=`"1.0`" encoding=`"UTF-8`"?>`r`n<Batch OnError=`"Continue`">`r`n"

        $listItems|%{ $cmdString += [string]::Format($cmdFormat, $_.ID, $_[[Microsoft.Sharepoint.SPBuiltInFieldId]::FileRef]) }
        $cmdString += "</Batch>`r`n"

        [Void]$w.ProcessBatchData($cmdString)
        Write-Host "Deleted $($len) items"
    }
} while($len -gt 0)