Here’s a site, by Lucian Wischik, that contains 101 Async Samples:
http://www.wischik.com/lu/AsyncSilverlight/AsyncSamples.html
There are examples in both C# and VB. Some examples have a selector that lets you toggle between .NET 4.0 and the new Async syntax. Each example has a run button so you can execute and see the return value. Throughout, you’ll see many different ways to use Async. I think it’s a very nice resource.
@JoeMayo