Microsoft brought some form to its cloud this morning, giving pricing details for Azure, its cloud computing platform.

The service is now in technical preview phase, but will go live at the Professional Developers Conference in the fall of this year, Microsoft said this morning.

With cloud computing, Microsoft hopes to persuade business customers to shift from hosting and running software on their own servers to hiring Microsoft to host and run the software for them. Here is a story we just ran explaining how the Ethiopian school system is using the cloud.

The pricing plan offers several options. Businesses could choose to pay based on usage, as with a utility; on a monthly basis, like a magazine subscription; or on an annual basis, like a car registration.

Here's asn example of what the first option, metered usage of Windows Azure, would cost:

Computing: 12 cents per hour

Storage: 15 cents per gigabyte
Storage transaction: 10 cents per 10,000KBandwidth: 10 cents in/15 cents out per gigabyte

It's like trying to figure out your monthly electrical bill based on the price of a kilowatt hour.
Prashant Ketkar, director of product marketing for Windows Azure, said not to focus on the price points. "While the actual per-unit price is interesting, in the end context, it doesn't really matter," he said. "They're only as significant as when you take a specific application and move to the Windows Azure environment."

Figuring out how much that would cost will require sitting down with Microsoft or a Microsoft partner (at the Worldwide Partners Conference happening today in New Orleans) and calculating the total cost of running an application, he said.

It's a lot less straightforward than at least one cloud competitor, SalesForce.com, which is offering cloud computing for $20 per user per month.

Here are more details on Microsoft's cloud pricing, if you really want to know:

SQL Azure
Web edition database, with 1 gigabyte relational database: $9.99

Business edition database, with 10 gigabyte relational database: $99.99
Bandwidth: 10 cents in/15 cents out per gigabyte

.NET Services
Messages: 15 cents per 100K message operations
Bandwidth: 10 cents in/15 cents out per gigabyte

Service Level Agreements
Compute connectivity: 99.95 percent guarantee
Storage: 99.9 percent guarantee
Automated service management