For those that haven’t seen it, Eric Lippert finished an amazing 8-part blog series in November on the new Asynchronous Programming APIs slated for the next version of C# and VB.  He shows you how to get started getting started with the CTP and how to determine if async makes sense for your application.

http://blogs.msdn.com/b/ericlippert/archive/tags/async/
Download the Asynchronous Programming CTP 
Send Async feedback and questions