Analysis of McKinsey's report on cloud computing

Last month McKinsey released a report called "Clearing the air on cloud computing" in which they conclude that corporations with large data center's could lose money if they move to the cloud. As per the report, the current cloud offerings are best suited for small and medium sized companies. Obviously these conclusions are based on some assumptions which unfortunately seem to be incorrect. Here are the detailed analysis(read rebuttal) of this report by James Hamilton and Lydia Leong. Very interesting reads.