Amazon.com's (AMZN -0.40%) Web Services platform is the longtime leader in outsourced cloud computing. Microsoft (MSFT 0.29%) Azure has barely made a dent in the market despite repeated assaults, but Rackspace Hosting (RAX) is gaining ground thanks to lower pricing and fanatical customer support.

That established trio of leaders had better make space for another big dog. Oracle (ORCL -0.46%) just announced a pair of cloud-computing services that will compete head-to-head with Amazon's AWS, Microsoft Azure, and Rackspace Cloud Hosting.

An AWS-like hosted solution will join a private cloud platform where the hardware is installed in the customer's data centers. Either way, Oracle is responsible for managing and operating the hardware while customers simply treat the platform as a blob of additional computing resources. This is in every way similar to what the current incumbents offer, except Oracle will prefer its own Sun Solaris-based equipment over the Linux and Windows solutions popular elsewhere.

These services may be the final payoff for Oracle's $7.4 billion Sun buyout. I'm still not convinced that the acquisition was a good idea. Sun's hardware is more of a distraction from Oracle's software core than a value-added expansion. But if CEO Larry Ellison plays his cards right, at least he found a ticket to ride around a host of hardware partners into the cloud-computing future.

If Oracle wants to copy somebody else's business model, the database expert could certainly pick far worse role models than Amazon. To help you understand why the leading e-tailer and budding IT giant garners recommendations from four separate Fool services, we've compiled a premium report on Amazon. In it, you'll see every rocket booster at Amazon's tail and every potential road block that lies ahead. Click here to get started.