Awesome, finally understand how Scheduler.Now is used, when I first saw that in Rx I knew you guys were using (or planning on using) virtual time but there seemed to be no documentation anywhere on the subject. Thanks for the explanation guys, extremely useful. Eagerly waiting on your unit tests so that I can start writing my asynchronous unit tests like that!
I just realised I can write unit tests that simulate "hot" observables that I don't normally have control over i.e. mouse moves etc, I can replace the original source with a mock observable that raises events a pre-determined times and pushes them through a virtual scheduler. Excellent!