Airlines buy futures contracts on jet fuel to mitigate the risk of price increases. Manufacturers do the same thing with electricity. So why can’t we buy a futures contract for the Cloud?

We’re not quite there yet, but a new capability from Amazon Web Services (AWS) paves the way for a full-blown market for Cloud instances: The Amazon EC2 Reserved Instance Marketplace. Yes, it’s still in beta, but Amazon is putting one more piece of the Cloud-as-utility paradigm in place.

To understand the context of this nascent marketplace, it’s important to get your head around how Amazon charges for Elastic Compute Cloud (EC2) instances. There are three core purchasing options: On-Demand Instances, Reserved Instances, and Spot Instances.

With On-Demand Instances you pay as you go with no up-front commitment. Alternately, you can make a low, one-time initial payment for Reserved Instances with a one- to three-year commitment, at a significantly lower rate than On-Demand Instances. With Spot Instances, you essentially bid on the type of instance you are looking for, setting a maximum cost. The cost for Spot Instances fluctuates, but if the cost exceeds your maximum, Amazon shuts the instance down.

The lowest cost option is the Reserved Instance — assuming, of course, you need each instance for the one to three year term that you commit to. But what if you need those instances only some of the time? That’s where the marketplace comes in.

Let’s say you need your Reserved Instances only during the holiday season. The rest of the year you can offer them to third parties who would bid to essentially sublet those instances from you when you’re not using them.

So far so good, but this story gets really interesting when you think about the opportunities that such a marketplace presents to speculators and other market players. You could theoretically buy up a number of Reserved Instances in hopes of selling them at a higher amount (a highly risky strategy, given Amazon’s history of lowering prices). The more lucrative play might be to establish a futures market. Companies pay a relatively small fee today to guarantee maximum pricing in the future. Or given the downward pricing pressure from Amazon, perhaps you want to buy a put option on the Reserved Instances you already purchased.

Today it’s too early to tell how this Cloud marketplace will pan out. But with their 12% cut of marketplace transactions, there’s no question the big winner, win or lose, will be Amazon.