自从用了ASP.NET2.0以后，这个问题被渐渐关注起来，目前的方法就是调用iisapp.vbs获取。
今天准备在我的文本转换工具里集成这个功能，于是，用C#实现了一下。

using System;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Management;
using System.Windows.Forms;

namespace TextConvertor
{
    /**//// <summary>
    /// W3wp 的摘要说明。
    /// </summary>
    public class W3wp
    {
        private W3wp(){}
        public static string GetAllW3wp(string input)
        {
            ObjectQuery oQuery = new ObjectQuery("select * from Win32_Process where Name=w3wp.exe");
            ManagementObjectSearcher oSearcher = new ManagementObjectSearcher(oQuery);
            ManagementObjectCollection oReturnCollection = oSearcher.Get();         
           
            string pid;
            string cmdLine;
            StringBuilder sb = new StringBuilder() ;
            foreach(ManagementObject oReturn in oReturnCollection)
            {               
                pid = oReturn.GetPropertyValue("ProcessId").ToString();               
                cmdLine = (string)oReturn.GetPropertyValue("CommandLine");

                string pattern = "-ap \"(.*)\"" ;
                Regex regex = new Regex(pattern, RegexOptions.IgnoreCase) ;
                Match match = regex.Match(cmdLine) ;
                string appPoolName = match.Groups[1].ToString() ;
                sb.AppendFormat("W3WP.exe PID: {0}   AppPoolId:{1}\r\n", pid, appPoolName );
            }

            return sb.ToString();
        }
    }
}

实现的原理和VBScript简直一模一样。
http://www.cnblogs.com/karoc/archive/2006/11/24/571245.html