That, or OpenStack. I know it's a bigger deal for telcos and wraps kvm, but it's very reliable, scalable, and has all the features a hosting provider would need.
You're right that it's not a hypervisor, but it's not an AWS emulator either. It's a collection of tightly coupled management layers for other open source projects that form a new, cohesive whole that can be competitive with AWS at a medium scale.