[jacquesm]

The only good use-case I know for AWS and it's ilk is if you need a 10,000 node cluster for a few hours to do some heavily compute intensive work which does not require a very large amount of data to be imported and exported afterwards. This is a pretty limited number of use cases but for those situations it absolutely rocks. Anything else I'd run the numbers very carefully.

[turnip1979]

I don't think that is correct. There are thousands of startups on AWS (an IAAS cloud) that don't run 10K node clusters. While they cost may be high, it is pay as you go. I have a rack full of computers at home and I still have some things served by AWS. The PAAS model (e.g. Heroku, Bluemix) is becoming popular today but those are often hosted in IAAS clouds.