WaitAll vs WhenAll

What is the difference between Task.WaitAll() and Task.WhenAll() from the Async CTP?
Can you provide some sample code to illustrate the different use cases?

Task.WaitAll blocks the current thread until everything has completed.

Task.WhenAll returns a task which represents the action of waiting until everything has completed.

That means that from an async method, you can use:

await Task.WhenAll(tasks);

... which means your method will continue when everything's completed, but you won't tie up a thread to just hang around until that time.

Stack Overflow Q#6123406, score: 773