The way I have done it is to switch your logo based on a CSS file.  You can add something like the following code to your skin .ascx file.

    Protected Overrides Sub OnLoad(ByVal e As EventArgs)
        MyBase.OnLoad(e)
       
       
        If System.Globalization.CultureInfo.CurrentCulture.ToString() = "es-ES" Then
            AttachCustomHeader("<link href='" + SkinPath + "css/my_layout-es-ES.css' rel='stylesheet' type='text/css' />")
        Else
            AttachCustomHeader("<link href='" + SkinPath + "css/my_layout.css' rel='stylesheet' type='text/css' />") 
        End If

 
    End Sub

    Sub AttachCustomHeader(ByVal CustomHeader As String)
        Dim HtmlHead As HtmlHead = Page.FindControl("Head")
        If Not (HtmlHead Is Nothing) Then
            HtmlHead.Controls.Add(New LiteralControl(CustomHeader))
        End If
    End Sub

I am not aware of an existing ML logo skin object, providing a logo per language. you might create your own logo Skin object or use inline code in oyur skin ascx to inject the culture into a fix logo name pattern.