Threading was never so easy since .NET 4 with the TPL has been released. I know I am a bit late but there are so many nice things which might still be new to many of us. The IEnumerable interface has become famous with the introduction of LINQ but many of us have not yet realized that IEnumerable<T> and  T[] or List<T> can be exchanged in many cases but there are cases where it is important to fall back to a pure IEnumerable<T> if you want to support lazy evaluation. .NET 4 has for example taken advantage of the lazy nature of IEnumerable<T> with the introduction of Directory.EnumerateFiles which returns immediately until the first file is found. Previously you had only the option to call Directory.GetFiles which does potentially search for a long time and will only return when all matching files have been found. This can make a big difference if you search recursively in a big file tree or a directory with many files. I had up to 40s delays in some applications which did process a large directory. 40s waiting time until you can process the first file is certainly not something you want. I did solve this issue in .NET 3.5 with DirectorySearcherAsync which did work quite well.

I'm needing to remember this to keep responsive UIs.