<asp:ImageButton id=ib runat=server CommandName="me" CommandArgument="imageButton
 />..
 void Grid_ItemCommand(Object sender, DataGridCommandEventArgs e) 
    {
        ImageButton ib = (ImageButton)e.CommandSource;
        Response.Write(ib.CommandName);
        //or
       //ImageButton ib = (ImageButton)e.Item.FindControl("ib");
    }