[Kazun]

$sity = "kemerovo"
$source = "http://www.google.com/ig/api?weather="+$sity
$xml = [xml](New-Object Net.WebClient).DownloadString($source)
"current","forecast" | %{ $xml.GetElementsByTagName("$_`_conditions")| %{$_.icon.data}}

или

$xml.GetElementsByTagName("icon") | Foreach {$_.data}

[Foreigner]

нужно получить все значения поля "icon data" »

Код:

$xml=new-object xml
$xml.load("http://www.google.com/ig/api?weather=Moscow")

$xml.xml_api_reply.weather.current_conditions.icon | % { $_.data }

$xml.xml_api_reply.weather | % { 

    $_.forecast_conditions | % { $_.icon.data }
    
}