methode async

public static List<Tweet> GetSearchResults(string searchString)
{
    using (WebClient web = new WebClient())
    {
        //More parameters then this. Most important is the page paramater. You can &page=1 to xxx. 
        //few parameters  in the url :     &rpp=100    for 100answer  |   %23 for hashtag | lang=en  for english msg......
        //  exemple: http://search.twitter.com/search.atom?lang=en&rpp=100&q=%23AnHashTag-filter:retweets
        // -filter:retweets   delete  duplicates
 
        string url = string.Format("http://search.twitter.com/search.atom?lang=en&q=%23{0}", searchString); //HttpUtility.UrlEncode(searchString)
                WebClient client = new WebClient();
 
        #region AsABrowser
        //Pretend to be Google Chrome
        //Pretending to be a browser instead of an app seems to make twitter respond faster
        client.Headers.Add("Accept: application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5");
        client.Headers.Add("Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3");
        client.Headers.Add("Accept-Language: en-US,en;q=0.8");
        client.Headers.Add("User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16");
        #endregion
        #region TweetFormat
        XDocument doc = XDocument.Load(url);
        XNamespace ns = "http://www.w3.org/2005/Atom";
        List<Tweet> tweets = (from item in doc.Descendants(ns + "entry")
                  select new Tweet
                  {
                     Id = item.Element(ns + "id").Value,
                     Published = DateTime.Parse(item.Element(ns + "published").Value),
                     Title = item.Element(ns + "title").Value,
                     Content = item.Element(ns + "content").Value,
                     Link = (from XElement x in item.Descendants(ns + "link")
                                where x.Attribute("type").Value == "text/html"
                                select x.Attribute("href").Value).First(),
                     Image = (from XElement x in item.Descendants(ns + "link")
                                where x.Attribute("type").Value == "image/png"
                                select x.Attribute("href").Value).First(),
                     Author = new Author()
                              {
                                 Name = item.Element(ns + "author").Element(ns + "name").Value,
                                 Uri = item.Element(ns + "author").Element(ns + "uri").Value
                              }
                }).ToList();
        return tweets;
        #endregion
     }
}