$navOpenInBackgroundTab = 0x1000;
$ie = new-object -com InternetExplorer.Application
$ie.Navigate2("http://blogs.msdn.com");
$ie.Navigate2("http://www.baidu.com",$navOpenInBackgroundTab);
$ie.Navigate2("http://www.google.com",$navOpenInBackgroundTab);
$ie.Navigate2("http://www.yahoo.com",$navOpenInBackgroundTab);
$ie.Visible = $true
延伸阅读:使用Powershell模拟IE的行为