Mesosphere itself is building a commercially supported product around the open source Apache Mesos project. Apache Mesos is a cluster management system that offers scheduling and resource sharing, a bit like Kubernetes itself, but at a much higher level. The open source project is used by several well-known companies, such as Twitter and Airbnb.
You can find out more information about the Mesos OS project and the Mesosphere offerings at the following sites:
Mesos, by its nature, is modular, and allows the use of different frameworks for a variety of platforms. A Kubernetes framework is now available, so we can take advantage of the cluster management in Mesos while still maintaining the useful application-level abstractions in K8s. Refer to the following link for more information: https://github.com/kubernetes-incubator/kube-mesos-framework.