Nick Carr has the full explanation. See here. Right now the only companies that can power a cloud are Google, Yahoo, Microsoft, IBM and Amazon. Figure Yahoo and Microsoft merge. That means four big back-end players and the two best will be Google and Amazon. Fact is we’ll play with any of them but we’re tight with Google and if I had to bet on a single horse it would be Google. So what would each of us do? It’s pretty simple. Money quote: “Apple would sell the hardware, and Google would subsidize the cost of supplying the servers with advertising, just as it does in other businesses in which it works.”