When should one use the following: Amazon EC2, Google App Engine, Microsoft Azure and Salesforce.com?

Question

I am asking this in very general sense. Both from cloud provider and cloud consumer\'s perspective. Also the question is not for any specific kind of application (in fact the in

Answer 1

Now how about Free Amazon EC2 for a year to do a better comparision. Check this out.

http://www.buzzingup.com/2010/10/amazon-announces-free-cloud-services-for-new-developers/