Ein Click beim ImageButton wird ja immer nach dem Page Load gefeuert und macht
ein postback.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Somnatic.USB;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            createTable();
        }
    }

    protected void createTable()
    {
        FtdiStatus fs = FtdiBitbang.GetState("DEV1232");

        for (int i = 0; i < 8; i++)
        {
            TableRow tr = new TableRow();
            TableCell tc1 = new TableCell();
            ImageButton ib1 = new ImageButton();

            if (fs.State[i] == true)
            {
                ib1.ImageUrl = "~/icons/on.png";
                ib1.CommandName = i.ToString();
                ib1.CommandArgument = Boolean.FalseString;
            }
            else
            {
                ib1.ImageUrl = "~/icons/off.png";
                ib1.CommandName = i.ToString();
                ib1.CommandArgument = Boolean.TrueString;

            }

            ib1.Command += new CommandEventHandler(ib1_Command);

            ib1.Command += new CommandEventHandler(ib_Command);
            tc1.Controls.Add(ib1);

            TableCell tc2 = new TableCell();
            tc2.Controls.Add(new LiteralControl(fs.Names[i]));

            tr.Cells.Add(tc1);
            tr.Cells.Add(tc2);

            statusTable.Rows.Add(tr);
        }   
    }

    void ib1_Command(object sender, CommandEventArgs e)
    {
        throw new Exception("The method or operation is not implemented.");
    }

    void ib_Command(object sender, CommandEventArgs e)
    {
        try
        {
            int number = Int32.Parse(e.CommandName);
            bool newState = Boolean.Parse((string)e.CommandArgument);

            FtdiBitbang.SetState("DEV1232", number, newState);

            createTable();
        }
        catch
        {
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        bool[] b = new bool[8];
        for (int i = 0; i < b.Length; i++)
        {
            b[i] = false;
        }
        FtdiBitbang.SetState("DEV1232", b);
    }
}

ib1.Command += new CommandEventHandler(ib1_Command);            
ib1.Command += new CommandEventHandler(ib_Command);