I think I understand your question, that you want to display a bunch of users and their last tweet - but keep checking if their last tweet has changed and update the screen when the user posts a tweet?
If so the answer is that you need to call the twitterapi asynchronously every so often and pull down the last status (tweet) for each user - and if it is a new one then use ajax to update the part of the screen with the old status (tweet) in it.
In TweetSharp if you have a List of friends, you can pull in their last tweet with something like:
string profileImageUrl = String.Empty;
string name = String.Empty;
string statusText = String.Empty;
string createdAt = String.Empty;
string screenName = String.Empty;
foreach (TwitterUser friend in friends)
{
try
{
profileImageUrl = String.IsNullOrEmpty(friend.ProfileImageUrl) ? "" : friend.ProfileImageUrl;
name = String.IsNullOrEmpty(friend.Name) ? "" : friend.Name;
statusText = (friend.Status == null || friend.Status.Text.Length == 0) ? "unknown" : friend.Status.Text; //stops nullreferenceexception on instance
createdAt = String.IsNullOrEmpty(friend.CreatedDate.ToString()) ? "" : friend.CreatedDate.ToString();
screenName = String.IsNullOrEmpty(friend.ScreenName) ? "" : friend.ScreenName;
}
catch (NullReferenceException)
{
profileImageUrl = "";
name = "unknown";
statusText = "unknown";
createdAt = "";
screenName = "unknown";
So you can display it on the screen initially.
Then use jquery (or javascript) to periodically hit a web service that reads the twitter api and then use the data returned to update the last tweet if it has changed.
Let me know if I have the wrong end of the stick.
EDIT:
An example of using Tweetsharp posting a new tweet to Twitter is:
var query = FluentTwitter.CreateRequest().AuthenticateAs(username,password).Statuses().Update("Posting status on StackOverflow").AsJson();