Newest to this table is ZeroStack, a freshly decloaked startup from VMware and AMD alumni, with a novel approach to how smaller and mid-tier outfits can manage OpenStack.
ZeroStack's idea is a mixture of an on-premises 2U appliance and a cloud-based SaaS portal. The appliance, a mixture of infrastructure and controller, is installed in the customer's data center, and administration is done through ZeroStack's cloud portal. Changes to the software are pushed out automatically to appliances from the cloud, and ZeroStack claims it can bring an existing OpenStack installation up to the latest revision of the product within two months of release.
Another touted advantage to ZeroStack's approach is that the OpenStack API set is still exposed through the appliance. After an organization gets its legs with OpenStack via ZeroStack's administration system, it can make more direct use of those APIs if it chooses.
ZeroStack is also adding features like the capacity for self-healing, so that any health problems with an OpenStack setup can be dealt with by way of the cloud service's collective intelligence.
One obvious implication of ZeroStack's offering is how it could serve as a starting point for the kind of truly open hybrid cloud OpenStack's advocates have been stumping for. ZeroStack doesn't have explicit plans for a hybrid play yet, but co-founder and CEO Ajay Gulati (ex-VMware) mentioned in an interview that they are going to be adding gateways to other public clouds such as Amazon.
For ZeroStack to stay in the game, it'll need to avoid the many pitfalls that have claimed other vendors in this space. Nebula comes most immediately to mind, especially after it crashed and burned by overestimating both the size of the market and its real nature. Mirantis, one of the big three names in OpenStack (next to Canonical and Red Hat), has an appliance strategy of its own that doesn't depend on any one particular hardware configuration and is not intended to become the bedrock of the company's revenue stream.
Gulati was quick to cite ways ZeroStack's approach differs from Nebula's. Aside from the technical differences between the Nebula and ZeroStack appliances (Nebula used a controller-node architecture; ZeroStack does not), ZeroStack "provides the actual server node on which workloads will run"), Nebula "[shipped] a packed Openstack and did not have any SaaS platform for operations and management."
Many OpenStack innovators have ended up being absorbed into the folds of one of OpenStack's major corporate backers -- e.g., IBM and Cisco acquiring of Blue Box Group and Piston Cloud, respectively, with those products subsumed into the OpenStack-powered cloud platforms of their new parents. For ZeroStack to avoid such a fate, it'll need to cut the same sort of path Mirantis is charting. That's a tough thing to do in a market whose existing size and growth only seems to allow for so many players and so much competition -- and where the demand for OpenStack tends to tilt more towards larger companies than smaller ones to begin with.