Starting today Amazon has decrease the amount paid by people that will predict their EC2 usage and decrease the on-demand (chaotic) usage. This good piece of news for all cloud (EC2) users signifies savings, but if you read a little more into it, you will see the actual underlying issue.
In a few days, the 24th of August of 2009 in the Australian Architecture Forum 2009, Dr. Anna Liu is going to disseminate a research that proves performance issues on different cloud providers, among them Amazon EC2, by a factor of 20 percent depending on the time of day.
If Amazon is on that conference, which it should, then I am sure this is move towards, normalizing the amount of unpredicted on-demand usage on their infrastructure.
Well. If you are a steady user of the EC2, go ahead and get a few reserved instances, because they are good offers. Only by utilizing your ec2 instance for 20% of the year you can get break even on the offer.
Enjoy clouding and keep me posted.