Is one cheaper or faster? The accompanying tables show the fastest and cheapest results in green and the slowest and priciest results in red. There's plenty of green in Google's table and plenty of red in Amazon's. Depending on how much you emphasize cost, the winners shift. Microsoft's Windows Azure machines start running green when you take the cost into account.
The freaky thing is that these results are far from consistent, even across the same architecture. Some of Microsoft's machines have green numbers and red numbers for the same machine. Google's one-CPU machine is full of green but runs red with the Tradesoap test. Is this a problem with the test or Google's handling of it? Who knows? Google's two-CPU machine is slowest on the Fop test — and Google's one-CPU machine is fastest. Go figure.
All of these results mean that doing your own testing is crucial. If you're intent on squeezing the most performance out of your nickel, you'll have to do some comparison testing and be ready to churn some numbers. The performance varies, and the price is only roughly correlated with usable power. There are a number of tasks where it would just be a waste of money to buy a fancier machine with extra cores because your algorithm can't use them. If you don't test these things, you can be wasting your budget.
It's also important to recognize that there can be quite a bit of markup hidden in these prices. For comparison, I also ran the benchmarks on a basic eight-core (AMD FX-8350) machine with 16GB of RAM on my desk. It was generally faster than Windows Azure's eight-core machine, just a bit slower than Google's eight-core machine, and about the same speed as Amazon's eight-core box. Yet the price was markedly different. The desktop machine cost about $600, and you should be able to put together a server in the same ballpark. The Google machine costs 82 cents per hour or about $610 for a 31-day month. You could start saving money after the first month if you build the machine yourself.
The price of the machine, though, is just part of the equation. Hosting the computer costs money, or more to the point, hosting lots of computers costs lots of money. The cloud services will be most attractive to companies that need big blocks of compute power for short sessions. If they pay by the hour and run the machines for only a short block of time, they can cut the costs dramatically. If your workload appears in short bursts, the markup isn't a problem because any machine you own will just sit there most of the day waiting, wasting cycles and driving up the air conditioning bills.