If you’re currently in the Amazon Elastic Compute Cloud (Amazon EC2) beta community, you and your peers can now benefit from a larger pool of pre-built Amazon Machine Images (AMIs) by sharing your AMIs with others. An AMI is a packaged environment that includes all the necessary bits to set up and boot Amazon EC2 instances. The more AMIs are shared, the faster the community can innovate. After you’ve shared your image, advertise it to other developers in the Resource Center. We hope you’ll contribute yours!
Amazon’s EC2 service runs on Xen. So ultimately you can grab ready to go VM images from other sources and use them on EC2 (only when you’re not remotely managing them on your own compute resources with the Virtual Workspace service, of course :-)).
There are good sources for many specialized images or base images (for customizing yourself) such as rBuilder and the VMware marketplace (VMware VMs can be converted to Xen images in most cases with an image copy and a little diligence).
rBuilder can deliver the built images directly to Amazon’s S3 service (where the EC2 images live as well), so I am hoping all of their appliances will be made available via the sharing options now available in the EC2 commandline interface.