Amazon has been a cloud computing giant for years, delivering infrastructure-as-a-service that lets businesses and developers build and host applications in Amazon data centers.

Now, the company is using its cloud to deliver virtual desktops to any Windows or Mac computer, iPad, Kindle Fire, or Android tablet. Announced today, it's called Amazon Workspaces, and while it's available in a limited preview, it's not yet ready for anyone who wants it.

Hosted virtual desktops have been around for years without making much of a dent in the market for physical PCs, owing to performance concerns and lack of offline access. Amazon will be running the service on infrastructure it's already built, so it probably isn't a huge extra cost. Server virtualization market leader VMware is also rolling out a desktops-as-a-service cloud.

Amazon Workspaces run on Amazon Elastic Compute Cloud virtual machines and deliver a Windows 7-like desktop with "Adobe Reader, Adobe Flash, Firefox, Internet Explorer 9, 7-Zip, the Java Runtime Environment (JRE), and other utilities," Amazon said. The higher-priced bundles include Microsoft Office Professional and Trend Micro security.

Each user gets 50GB to 100GB of cloud storage (which is mapped to the D: drive), one or two virtual CPUs, and 3.75GB or 7.5GB of memory. Amazon delivers the desktops using the PCoIP remote display protocol, which is also used by VMware's virtual desktop platform. Amazon Workspaces' total prices range from $35 to $75 per user per month.

The desktops will be accessed from client applications on Windows and Mac computers, or the aforementioned tablets. They're designed with security in mind—possible use cases include to provide desktops for temporary workers or to give developers "the tools that they need to have in order to be productive, while ensuring that source code and other intellectual property are protected," Amazon said. The workspaces can be mapped into a corporation's Active Directory deployment to help businesses manage user credentials and permissions.

Amazon made the desktop announcement at its annual re:Invent conference. In other news, the company announced AppStream, which is designed to stream complex and graphically rich applications from the cloud to just about any device, even ones with limited CPU, storage, and graphics rendering capabilities. The applications run on virtual machines powered by Nvidia GPUs and Intel Sandy Bridge processors.