According to http://stackoverflow.com/a/868290/259130

    function directory-summary($dir=".") { 
      get-childitem $dir | 
        % { $f = $_ ; 
            get-childitem -r $_.FullName | 
               measure-object -property length -sum | 
                 select @{Name="Name";Expression={$f}},Sum}
    }

I could get a shorter non exact version if I was on windows.