The new C# 5.0 proposes to bring asynchronous keywords, which I believe works like macros to turn imperative code into continuations. The “await” operator us

The new C# 5.0 proposes to bring asynchronous keywords, which I believe works like macros to turn imperative code into continuations. The “await” operator used twice in that method does not mean “this method now blocks the current thread until the asynchronous operation returns”. That would be making the asynchronous operation back into a synchronous operation, which is precisely what we are attempting to avoid. Rather, it means the opposite of that; it means “if the task we are awaiting has not yet completed then sign up the rest of this method as the continuation of that task, and then return to your caller immediately; the task will invoke the continuation when it completes.” http://blogs.msdn.com/b/ericlippert/archive/2010/10/29/asynchronous-programming-in-c-5-0-part-two-whence-await.aspx http://blogs.msdn.com/b/ericlippert/archive/2010/10/29/async... async void ArchiveDocuments(List<Url> urls) { Task archive = null; for(int i = 0; i < urls.Count; ++i) { var document = await FetchAsync(urls[i]); if (archive != null) await archive; archive = ArchiveAsync(document); } } Microsoft has been very lucky to have someone like Anders Hejlsberg, who has steadily brought a stream of features to an enterprise programming language.