I've found another problem. If you create a spot request at any price, it's forever either pending-evaluation or pending-fullfilment, but no instance is created. I had 3 in pending-fullfilment for 30 minutes, after that the status changed back to pending-evaluation.
I just spun up a cc2.8xlarge instance (in oregon) to test and it worked fine. So they are still available. Took a minute or so (like always).
Unless they somehow disabled them for the free credit, it should still work. Just make sure you are using linux instances (looks like they are no longer available for windows) and you put in a price *ABOVE* the spot price (you are only charged the spot rate but if you go too close it will never be fulfilled or worse your instances will be terminated). i.e. 0.30 or even 0.350